Compilare: user.c: In function ‘Matrix_3D_Multiply’: user.c:16:1: warning: implicit declaration of function ‘memset’ [-Wimplicit-function-declaration] memset(C, 0, 9 * sizeof(long long)); ^ user.c:16:1: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] user.c:25:1: warning: implicit declaration of function ‘memcpy’ [-Wimplicit-function-declaration] memcpy(A, C, 9 * sizeof(long long)); ^ user.c:25:1: warning: incompatible implicit declaration of built-in function ‘memcpy’ [enabled by default] user.c: In function ‘Expo’: user.c:40:1: warning: incompatible implicit declaration of built-in function ‘memcpy’ [enabled by default] memcpy(A, result, 9 * sizeof(long long)); ^ user.c: In function ‘main’: user.c:55:5: warning: incompatible implicit declaration of built-in function ‘memcpy’ [enabled by default] memcpy(MatrixA, CopyOfA, 9 * sizeof(long long)); ^ user.c: In function ‘Expo’: user.c:41:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.c: In function ‘main’: user.c:51:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld", &T); ^ user.c:54:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lld %lld %lld %lld %lld %lld %lld", &X, &Y, &Z, &A, &B, &C, &N); ^