Compilare: user.c: In function ‘main’: user.c:19:5: warning: implicit declaration of function ‘close’ [-Wimplicit-function-declaration] close(in); ^ user.c:16:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &a); ^ user.c:17:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &b); ^