Compilare: user.c: In function ‘main’: user.c:49:1: warning: implicit declaration of function ‘strlen’ [-Wimplicit-function-declaration] N[0] = strlen(stringN); ^ user.c:49:8: warning: incompatible implicit declaration of built-in function ‘strlen’ [enabled by default] N[0] = strlen(stringN); ^ user.c:46:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%s", stringN); ^ user.c:47:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &D); ^