Compilare: user.c: In function ‘main’: user.c:16:1: warning: implicit declaration of function ‘memset’ [-Wimplicit-function-declaration] memset(digits, 0, 40); ^ user.c:16:1: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] user.c:54:5: warning: implicit declaration of function ‘isdigit’ [-Wimplicit-function-declaration] if(!isdigit(ch)){ ^ user.c:15:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%d", &length); ^