use fprintf() instead of printf() in main

1 files changed, 4 insertions, 4 deletions

diff --git a/src/main.c b/src/main.c
index 14c6c49..d4b2431 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4,15 +4,15 @@
 
 int main(int argc, char **argv) {
     if(argc < 2) {
-        printf("Missing argument: input file\n");
-        printf("Usage:\n");
-        printf(" %s <filename>\n", argv[0]);
+        fprintf(stderr, "Missing argument: input file\n");
+        fprintf(stderr, "Usage:\n");
+        fprintf(stderr, " %s <filename>\n", argv[0]);
         return 1;
     }
 
     Graph *g = graph_read(argv[1]);
     if (!g) {
-        printf("%s: %s: No such file\n", argv[0], argv[1]);
+        fprintf(stderr, "%s: %s: No such file\n", argv[0], argv[1]);
         return 2;
     }