Why does my function returning long long, returns 705032704?

Question

I'm working on a code that returns the value in base 10 for a given string and base. But for large values of numbers in base 10, my program just returns 705032704 instead.

#include <iostream>
#include <string.h>
#include <stdio.h>
using namespace std;

    int val(char c)
    {
        if (c >= '0' && c <= '9')
            return (int)c - '0';
        else
            return (int)c - 'A' + 10;
    }

            long long basemachine(int base, char *str) {         //this function returns answer in base 10
            int len=strlen(str); int power=1; long long num=0;

           for (int i=len-1; i>=0; i--) {
              num+= val(str[i])*power;
              power=power*base;
           }
           return num;
         }

int main() {
    char str1[]="2P6X2MU";
    char str2[]="6PMP5GK";
    long long n=basemachine(35, str1);
    long long m=basemachine(30, str2);
    cout<<n<<" "<<m;
    return 0;
}

(2P6X2MU) base 35 and (6PMP5GK) base 30 both = 5000000000
But my code is returning 705032704 705032704 instead of 5000000000 5000000000
How do I fix this?

Answer 1

power is of type int instead of long long.

Demo