Compilare: user.c: In function ‘HugeMultiply’: user.c:30:1: warning: implicit declaration of function ‘memset’ [-Wimplicit-function-declaration] memset(C, 0, sizeof(C)); ^ user.c:30:1: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] user.c:40:1: warning: implicit declaration of function ‘memcpy’ [-Wimplicit-function-declaration] memcpy(aux, C, sizeof(C)); ^ user.c:40:1: warning: incompatible implicit declaration of built-in function ‘memcpy’ [enabled by default] user.c: In function ‘HugeExpo’: user.c:57:1: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] memset(result, 0, 4000 * sizeof(long long)); ^ user.c:70:1: warning: incompatible implicit declaration of built-in function ‘memcpy’ [enabled by default] memcpy(aux, result, sizeof(result)); ^ user.c: At top level: user.c:73:1: warning: return type defaults to ‘int’ [enabled by default] main(){ ^ user.c: In function ‘main’: user.c:98:1: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] memset(Two, 0, 4000 * sizeof(long long)); ^ user.c:80:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &m); ^ user.c:81:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &n); ^