Why " rand ()" don't work? Who knows?

Question

#include <iostream>
using namespace std;
int main(int argc, const char*argv[]) {
int a;
a=1+rand()%10;
cout <<a<<endl;
return 0;
}

Answer 1

You need to provide a seed for rand to initialize the random number generator.
#include <iostream>
using namespace std;
int main(int argc, const char*argv[]) {
int a;
srand(time(NULL)); // seed rand with time
a = rand() % 10 + 1;
cout << a << endl;
return 0;
}

Answer 2

Thanks!