From 1f99dc511df8a2008a79331a32b3ebf300ae8722 Mon Sep 17 00:00:00 2001
From: Shahram Najm <masn@ecmwf.int>
Date: Thu, 14 May 2020 20:21:31 +0100
Subject: [PATCH] Examples: write errors to stderr

---
 examples/C/bufr_attributes.c         |  4 ++--
 examples/C/bufr_copy_data.c          |  8 ++++----
 examples/C/bufr_expanded.c           |  4 ++--
 examples/C/bufr_get_keys.c           |  4 ++--
 examples/C/bufr_get_string_array.c   |  6 +++---
 examples/C/bufr_keys_iterator.c      |  6 +++---
 examples/C/bufr_missing.c            |  4 ++--
 examples/C/bufr_read_header.c        |  4 ++--
 examples/C/bufr_read_scatterometer.c | 10 +++++-----
 examples/C/bufr_read_synop.c         |  5 ++---
 examples/C/bufr_read_temp.c          | 10 +++++-----
 examples/C/bufr_set_keys.c           |  4 ++--
 examples/C/get_product_kind.c        |  4 ++--
 examples/C/grib_ensemble_index.c     |  2 +-
 examples/C/grib_get_data.c           | 10 +++++-----
 examples/C/grib_get_keys.c           |  4 ++--
 examples/C/grib_index.c              |  8 ++++----
 examples/C/grib_iterator.c           |  2 +-
 examples/C/grib_keys_iterator.c      |  4 ++--
 examples/C/grib_list.c               |  4 ++--
 examples/C/grib_multi.c              |  2 +-
 examples/C/grib_precipitation.c      |  2 +-
 examples/C/grib_precision.c          |  6 +++---
 examples/C/grib_print_data.c         |  4 ++--
 examples/C/grib_set_bitmap.c         |  7 +++----
 examples/C/grib_set_data.c           |  2 +-
 examples/C/grib_set_keys.c           |  6 +++---
 examples/C/set_missing.c             |  6 +++---
 examples/C/values_check.c            |  6 +++---
 29 files changed, 73 insertions(+), 75 deletions(-)

diff --git a/examples/C/bufr_attributes.c b/examples/C/bufr_attributes.c
index d234a2b45..1fad88652 100644
--- a/examples/C/bufr_attributes.c
+++ b/examples/C/bufr_attributes.c
@@ -36,14 +36,14 @@ int main(int argc, char* argv[])
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/bufr_copy_data.c b/examples/C/bufr_copy_data.c
index b2447c21f..eb816163f 100644
--- a/examples/C/bufr_copy_data.c
+++ b/examples/C/bufr_copy_data.c
@@ -53,7 +53,7 @@ int main(int argc, char* argv[])
     }
     ho = codes_bufr_handle_new_from_samples(NULL, sampleName);
     if (ho == NULL) {
-        fprintf(stderr, "ERROR creating BUFR from %s\n", sampleName);
+        fprintf(stderr, "Error: creating BUFR from %s\n", sampleName);
         fclose(f);
         return 1;
     }
@@ -80,14 +80,14 @@ int main(int argc, char* argv[])
 
     while ((h = codes_handle_new_from_file(0, f, PRODUCT_BUFR, &err)) != NULL) {
         if (!h) {
-            printf("ERROR: Unable to create BUFR handle\n");
+            fprintf(stderr, "Error: Unable to create BUFR handle\n");
             return 1;
         }
         /* codes_copy_key(h,ho,"unexpandedDescriptors",0); */
         err = codes_set_long(h, "unpack", 1);
         if (err) {
-            printf("ERROR: Unable to unpack BUFR message. Quitting\n");
-            printf("       %s\n", codes_get_error_message(err));
+            fprintf(stderr, "Error: Unable to unpack BUFR message. Quitting\n");
+            fprintf(stderr, "       %s\n", codes_get_error_message(err));
             return 1;
         }
 
diff --git a/examples/C/bufr_expanded.c b/examples/C/bufr_expanded.c
index 53f393971..a18d1040c 100644
--- a/examples/C/bufr_expanded.c
+++ b/examples/C/bufr_expanded.c
@@ -43,14 +43,14 @@ int main(int argc, char* argv[])
     /* open bufr file */
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/bufr_get_keys.c b/examples/C/bufr_get_keys.c
index e12538c2a..c475c8c6b 100644
--- a/examples/C/bufr_get_keys.c
+++ b/examples/C/bufr_get_keys.c
@@ -36,14 +36,14 @@ int main(int argc, char* argv[])
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/bufr_get_string_array.c b/examples/C/bufr_get_string_array.c
index 5c2eb1a0a..1220f04c7 100644
--- a/examples/C/bufr_get_string_array.c
+++ b/examples/C/bufr_get_string_array.c
@@ -29,14 +29,14 @@ int main(int argc, char* argv[])
 
     FILE* in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
@@ -49,7 +49,7 @@ int main(int argc, char* argv[])
         CODES_CHECK(codes_get_size(h, "stationOrSiteName", &len), 0);
         strArray = (char**)malloc(len * sizeof(char*));
         if (!strArray) {
-            printf("Error: Could not allocate memory\n");
+            fprintf(stderr, "Error: Could not allocate memory\n");
             return 1;
         }
         CODES_CHECK(codes_get_string_array(h, "stationOrSiteName", strArray, &size), 0);
diff --git a/examples/C/bufr_keys_iterator.c b/examples/C/bufr_keys_iterator.c
index 780456333..d3544873a 100644
--- a/examples/C/bufr_keys_iterator.c
+++ b/examples/C/bufr_keys_iterator.c
@@ -47,7 +47,7 @@ int main(int argc, char* argv[])
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
@@ -55,7 +55,7 @@ int main(int argc, char* argv[])
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         codes_bufr_keys_iterator* kiter = NULL;
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
@@ -68,7 +68,7 @@ int main(int argc, char* argv[])
         /* get BUFR key iterator */
         kiter = codes_bufr_keys_iterator_new(h, 0);
         if (!kiter) {
-            printf("ERROR: Unable to create BUFR keys iterator\n");
+            fprintf(stderr, "Error: Unable to create BUFR keys iterator\n");
             exit(1);
         }
 
diff --git a/examples/C/bufr_missing.c b/examples/C/bufr_missing.c
index 10a582924..2ff58225f 100644
--- a/examples/C/bufr_missing.c
+++ b/examples/C/bufr_missing.c
@@ -31,14 +31,14 @@ int main(int argc, char* argv[])
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/bufr_read_header.c b/examples/C/bufr_read_header.c
index c29482117..125d521ca 100644
--- a/examples/C/bufr_read_header.c
+++ b/examples/C/bufr_read_header.c
@@ -39,14 +39,14 @@ int main(int argc, char* argv[])
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/bufr_read_scatterometer.c b/examples/C/bufr_read_scatterometer.c
index 914fe0753..244d8878f 100644
--- a/examples/C/bufr_read_scatterometer.c
+++ b/examples/C/bufr_read_scatterometer.c
@@ -40,14 +40,14 @@ int main(int argc, char* argv[])
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* Loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
@@ -76,7 +76,7 @@ int main(int argc, char* argv[])
         /* Check the size (including all the subsets) */
         CODES_CHECK(codes_get_size(h, key_name, &len), 0);
         if (len != numObs) {
-            printf("inconsistent number of %s values found!\n", key_name);
+            fprintf(stderr, "Error: inconsistent number of %s values found!\n", key_name);
             return 1;
         }
 
@@ -93,7 +93,7 @@ int main(int argc, char* argv[])
         /* Check the size (including all the subsets) */
         CODES_CHECK(codes_get_size(h, key_name, &len), 0);
         if (len != numObs) {
-            printf("inconsistent number of %s values found!\n", key_name);
+            fprintf(stderr, "Error: inconsistent number of %s values found!\n", key_name);
             return 1;
         }
 
@@ -107,7 +107,7 @@ int main(int argc, char* argv[])
         /* Check the size (including all the subsets) */
         CODES_CHECK(codes_get_size(h, key_name, &len), 0);
         if (len != numObs) {
-            printf("inconsistent number of %s values found!\n", key_name);
+            fprintf(stderr, "Error: inconsistent number of %s values found!\n", key_name);
             return 1;
         }
 
diff --git a/examples/C/bufr_read_synop.c b/examples/C/bufr_read_synop.c
index 280c17bba..8e0d8557a 100644
--- a/examples/C/bufr_read_synop.c
+++ b/examples/C/bufr_read_synop.c
@@ -21,7 +21,6 @@
  * example. It is advised to use bufr_dump to understand the structure of the messages.
  */
 
-
 #include "eccodes.h"
 
 int main(int argc, char* argv[])
@@ -39,14 +38,14 @@ int main(int argc, char* argv[])
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/bufr_read_temp.c b/examples/C/bufr_read_temp.c
index 2b8247459..0e7056372 100644
--- a/examples/C/bufr_read_temp.c
+++ b/examples/C/bufr_read_temp.c
@@ -47,14 +47,14 @@ int main(int argc, char* argv[])
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     /* Loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
@@ -104,7 +104,7 @@ int main(int argc, char* argv[])
         /* Check the size */
         CODES_CHECK(codes_get_size(h, key_name, &len), 0);
         if (len != sigt_len) {
-            printf("inconsistent number of geopotential values found!\n");
+            fprintf(stderr, "Error: inconsistent number of geopotential values found!\n");
             free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
             return 1;
         }
@@ -114,7 +114,7 @@ int main(int argc, char* argv[])
 
         /* Get temperature */
         if (len != sigt_len) { /* Check the size */
-            printf("inconsistent number of temperature values found!\n");
+            fprintf(stderr, "Error: inconsistent number of temperature values found!\n");
             free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
             return 1;
         }
@@ -125,7 +125,7 @@ int main(int argc, char* argv[])
 
         /* Get dew point */
         if (len != sigt_len) { /* Check the size */
-            printf("inconsistent number of dewpoint temperature values found!\n");
+            fprintf(stderr, "Error: inconsistent number of dewpoint temperature values found!\n");
             free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
             return 1;
         }
diff --git a/examples/C/bufr_set_keys.c b/examples/C/bufr_set_keys.c
index b56d490c3..a3f383d4d 100644
--- a/examples/C/bufr_set_keys.c
+++ b/examples/C/bufr_set_keys.c
@@ -48,7 +48,7 @@ int main(int argc, char* argv[])
     out = fopen(argv[1], "wb");
 
     if (!in || !out) {
-        perror("ERROR: unable to open files");
+        perror("Error: unable to open files");
         if (out) fclose(out);
         if (in) fclose(in);
         return 1;
@@ -57,7 +57,7 @@ int main(int argc, char* argv[])
     /* loop over the messages in the bufr file */
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/get_product_kind.c b/examples/C/get_product_kind.c
index 30b471352..6ce47d6d2 100644
--- a/examples/C/get_product_kind.c
+++ b/examples/C/get_product_kind.c
@@ -36,13 +36,13 @@ int main(int argc, char* argv[])
     infile = argv[1];
     in     = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_ANY, &err)) != NULL || err != CODES_SUCCESS) {
         if (h == NULL) {
-            printf("Error: unable to create handle for message %d\n", cnt);
+            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
             cnt++;
             continue;
         }
diff --git a/examples/C/grib_ensemble_index.c b/examples/C/grib_ensemble_index.c
index 1d461f76c..0de9fc260 100644
--- a/examples/C/grib_ensemble_index.c
+++ b/examples/C/grib_ensemble_index.c
@@ -65,7 +65,7 @@ int main(int argc, char* argv[])
         /* create handle for next GRIB message */
         h = codes_handle_new_from_index(index, &ret);
         if (ret) {
-            printf("Error: %s\n", codes_get_error_message(ret));
+            fprintf(stderr, "Error: %s\n", codes_get_error_message(ret));
             exit(ret);
         }
 
diff --git a/examples/C/grib_get_data.c b/examples/C/grib_get_data.c
index 04ca6f14c..7670aa66e 100644
--- a/examples/C/grib_get_data.c
+++ b/examples/C/grib_get_data.c
@@ -32,14 +32,14 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open input file %s\n", filename);
+        fprintf(stderr, "Error: unable to open input file %s\n", filename);
         return 1;
     }
 
     /* create new handle from a message in a file */
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", filename);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", filename);
         return 1;
     }
 
@@ -48,18 +48,18 @@ int main(int argc, char** argv)
 
     lats = (double*)malloc(numberOfPoints * sizeof(double));
     if (!lats) {
-        printf("unable to allocate %ld bytes\n", (long)(numberOfPoints * sizeof(double)));
+        fprintf(stderr, "Error: unable to allocate %ld bytes\n", (long)(numberOfPoints * sizeof(double)));
         return 1;
     }
     lons = (double*)malloc(numberOfPoints * sizeof(double));
     if (!lons) {
-        printf("unable to allocate %ld bytes\n", (long)(numberOfPoints * sizeof(double)));
+        fprintf(stderr, "Error: unable to allocate %ld bytes\n", (long)(numberOfPoints * sizeof(double)));
         free(lats);
         return 1;
     }
     values = (double*)malloc(numberOfPoints * sizeof(double));
     if (!values) {
-        printf("unable to allocate %ld bytes\n", (long)(numberOfPoints * sizeof(double)));
+        fprintf(stderr, "Error: unable to allocate %ld bytes\n", (long)(numberOfPoints * sizeof(double)));
         free(lats);
         free(lons);
         return 1;
diff --git a/examples/C/grib_get_keys.c b/examples/C/grib_get_keys.c
index 916a48171..59d5034fe 100644
--- a/examples/C/grib_get_keys.c
+++ b/examples/C/grib_get_keys.c
@@ -46,14 +46,14 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
     /* create new handle from the first message in the file*/
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", filename);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", filename);
         return 1;
     }
     fclose(in);
diff --git a/examples/C/grib_index.c b/examples/C/grib_index.c
index 1faf3cd92..1967948d8 100644
--- a/examples/C/grib_index.c
+++ b/examples/C/grib_index.c
@@ -45,14 +45,14 @@ int main(int argc, char* argv[])
     /* Create an index given set of keys*/
     index = codes_index_new(0, "shortName,level,number,step", &ret);
     if (ret) {
-        printf("error: %s\n", codes_get_error_message(ret));
+        fprintf(stderr, "Error: %s\n", codes_get_error_message(ret));
         exit(ret);
     }
 
     /* Indexes a file */
     ret = codes_index_add_file(index, infile);
     if (ret) {
-        printf("error: %s\n", codes_get_error_message(ret));
+        fprintf(stderr, "Error: %s\n", codes_get_error_message(ret));
         exit(ret);
     }
     printf("end indexing...\n");
@@ -128,7 +128,7 @@ int main(int argc, char* argv[])
                     while ((h = codes_handle_new_from_index(index, &ret)) != NULL) {
                         count++;
                         if (ret) {
-                            printf("error: %d\n", ret);
+                            fprintf(stderr, "Error: %d\n", ret);
                             exit(ret);
                         }
                         lenshortName = 200;
@@ -143,7 +143,7 @@ int main(int argc, char* argv[])
                         codes_handle_delete(h);
                     }
                     if (ret && ret != GRIB_END_OF_INDEX) {
-                        printf("error: %s\n", codes_get_error_message(ret));
+                        fprintf(stderr, "Error: %s\n", codes_get_error_message(ret));
                         exit(ret);
                     }
                 }
diff --git a/examples/C/grib_iterator.c b/examples/C/grib_iterator.c
index 122160817..92d8650f6 100644
--- a/examples/C/grib_iterator.c
+++ b/examples/C/grib_iterator.c
@@ -46,7 +46,7 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
diff --git a/examples/C/grib_keys_iterator.c b/examples/C/grib_keys_iterator.c
index dcff27c21..62a71f8a8 100644
--- a/examples/C/grib_keys_iterator.c
+++ b/examples/C/grib_keys_iterator.c
@@ -69,13 +69,13 @@ int main(int argc, char* argv[])
         msg_count++;
         printf("-- GRIB N. %d --\n", msg_count);
         if (!h) {
-            printf("ERROR: Unable to create grib handle\n");
+            fprintf(stderr, "Error: Unable to create grib handle\n");
             exit(1);
         }
 
         kiter = codes_keys_iterator_new(h, key_iterator_filter_flags, name_space);
         if (!kiter) {
-            printf("ERROR: Unable to create keys iterator\n");
+            fprintf(stderr, "Error: Unable to create keys iterator\n");
             exit(1);
         }
 
diff --git a/examples/C/grib_list.c b/examples/C/grib_list.c
index aabfc0381..9ce006919 100644
--- a/examples/C/grib_list.c
+++ b/examples/C/grib_list.c
@@ -37,14 +37,14 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open input file %s\n", filename);
+        fprintf(stderr, "Error: unable to open input file %s\n", filename);
         return 1;
     }
 
     /* create new handle from a message in a file*/
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", filename);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", filename);
     }
 
     CODES_CHECK(codes_get_long(h, "numberOfContributingSpectralBands", &numberOfContributingSpectralBands), 0);
diff --git a/examples/C/grib_multi.c b/examples/C/grib_multi.c
index 1f29975a6..93ea8ad02 100644
--- a/examples/C/grib_multi.c
+++ b/examples/C/grib_multi.c
@@ -37,7 +37,7 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
diff --git a/examples/C/grib_precipitation.c b/examples/C/grib_precipitation.c
index 2a0431502..5e6297364 100644
--- a/examples/C/grib_precipitation.c
+++ b/examples/C/grib_precipitation.c
@@ -47,7 +47,7 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "ERROR: unable to open file %s\n", filename);
         return 1;
     }
 
diff --git a/examples/C/grib_precision.c b/examples/C/grib_precision.c
index a1838cf22..d24f20793 100644
--- a/examples/C/grib_precision.c
+++ b/examples/C/grib_precision.c
@@ -47,13 +47,13 @@ int main(int argc, char** argv)
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open input file %s\n", infile);
+        fprintf(stderr, "Error: unable to open input file %s\n", infile);
         return 1;
     }
 
     out = fopen(outfile, "wb");
     if (!out) {
-        printf("ERROR: unable to open output file %s\n", outfile);
+        fprintf(stderr, "Error: unable to open output file %s\n", outfile);
         fclose(in);
         return 1;
     }
@@ -61,7 +61,7 @@ int main(int argc, char** argv)
     /* create a new handle from a message in a file */
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", infile);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", infile);
     }
 
     /* bitsPerValue before changing the packing parameters */
diff --git a/examples/C/grib_print_data.c b/examples/C/grib_print_data.c
index 915ea4cac..beab7a4d6 100644
--- a/examples/C/grib_print_data.c
+++ b/examples/C/grib_print_data.c
@@ -41,14 +41,14 @@ int main(int argc, char** argv)
 
     in = fopen(filename, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", filename);
+        fprintf(stderr, "Error: unable to open file %s\n", filename);
         return 1;
     }
 
     /* create new handle from a message in a file*/
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", filename);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", filename);
     }
 
     /* get the size of the values array*/
diff --git a/examples/C/grib_set_bitmap.c b/examples/C/grib_set_bitmap.c
index 16baafe9e..2db451cff 100644
--- a/examples/C/grib_set_bitmap.c
+++ b/examples/C/grib_set_bitmap.c
@@ -13,7 +13,6 @@
  *
  * Description: how to set a bitmap in a GRIB message
  *
- *
  */
 
 #include <stdio.h>
@@ -39,20 +38,20 @@ int main(int argc, char** argv)
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open input file %s\n", infile);
+        fprintf(stderr, "Error: unable to open input file %s\n", infile);
         return 1;
     }
 
     out = fopen(outfile, "wb");
     if (!out) {
-        printf("ERROR: unable to open output file %s\n", outfile);
+        fprintf(stderr, "Error: unable to open output file %s\n", outfile);
         fclose(in);
         return 1;
     }
 
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", infile);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", infile);
     }
 
     CODES_CHECK(codes_set_double(h, "missingValue", missing), 0);
diff --git a/examples/C/grib_set_data.c b/examples/C/grib_set_data.c
index 2b5918763..a23bdf0ac 100644
--- a/examples/C/grib_set_data.c
+++ b/examples/C/grib_set_data.c
@@ -49,7 +49,7 @@ int main(int argc, char** argv)
     printf("Using samples path: %s\n", samples_path);
     h = codes_grib_handle_new_from_samples(0, sample_filename);
     if (h == NULL) {
-        printf("Error: unable to create handle from sample file %s\n", sample_filename);
+        fprintf(stderr, "Error: unable to create handle from sample file %s\n", sample_filename);
         exit(1);
     }
 
diff --git a/examples/C/grib_set_keys.c b/examples/C/grib_set_keys.c
index f800dea93..bd623008f 100644
--- a/examples/C/grib_set_keys.c
+++ b/examples/C/grib_set_keys.c
@@ -38,13 +38,13 @@ int main(int argc, char** argv)
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open file %s\n", infile);
+        fprintf(stderr, "Error: unable to open file %s\n", infile);
         return 1;
     }
 
     out = fopen(outfile, "wb");
     if (!out) {
-        printf("ERROR: unable to open file %s\n", outfile);
+        fprintf(stderr, "Error: unable to open file %s\n", outfile);
         fclose(in);
         return 1;
     }
@@ -52,7 +52,7 @@ int main(int argc, char** argv)
     /* create a new handle from a message in a file */
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", infile);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", infile);
     }
 
     /* set centre as a long */
diff --git a/examples/C/set_missing.c b/examples/C/set_missing.c
index cae2ab76a..487306999 100644
--- a/examples/C/set_missing.c
+++ b/examples/C/set_missing.c
@@ -36,13 +36,13 @@ int main(int argc, char** argv)
 
     in = fopen(infile, "rb");
     if (!in) {
-        printf("ERROR: unable to open input file %s\n", infile);
+        fprintf(stderr, "Error: unable to open input file %s\n", infile);
         return 1;
     }
 
     out = fopen(outfile, "wb");
     if (!out) {
-        printf("ERROR: unable to open output file %s\n", outfile);
+        fprintf(stderr, "Error: unable to open output file %s\n", outfile);
         fclose(in);
         return 1;
     }
@@ -50,7 +50,7 @@ int main(int argc, char** argv)
     /* create a new handle from a message in a file */
     h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
     if (h == NULL) {
-        printf("Error: unable to create handle from file %s\n", infile);
+        fprintf(stderr, "Error: unable to create handle from file %s\n", infile);
     }
 
     CODES_CHECK(codes_set_string(h, "typeOfFirstFixedSurface", str, &str_len), 0);
diff --git a/examples/C/values_check.c b/examples/C/values_check.c
index abb155487..0db03e54d 100644
--- a/examples/C/values_check.c
+++ b/examples/C/values_check.c
@@ -29,7 +29,7 @@ int main(int argc, char* argv[])
 
     h = codes_handle_new_from_file(c, f, PRODUCT_GRIB, &err);
     if (!h) {
-        printf("unable to create handle from file %s\n", infile);
+        fprintf(stderr, "unable to create handle from file %s\n", infile);
         exit(err);
     }
     fclose(f);
@@ -48,7 +48,7 @@ int main(int argc, char* argv[])
         for (i = 0; i < nvalues; i++) {
             if (values[i].error == err) name = (char*)values[i].name;
         }
-        printf("ERROR: \"%s\" %s\n", name, codes_get_error_message(err));
+        fprintf(stderr, "Error: \"%s\" %s\n", name, codes_get_error_message(err));
     }
 
     values[1].name = "levelll";
@@ -57,7 +57,7 @@ int main(int argc, char* argv[])
         for (i = 0; i < nvalues; i++) {
             if (values[i].error == err) name = (char*)values[i].name;
         }
-        printf("ERROR: \"%s\" %s\n", name, codes_get_error_message(err));
+        fprintf(stderr, "Error: \"%s\" %s\n", name, codes_get_error_message(err));
     }
 
     return 0;