# Convert all lowercase characters to uppercase whose ASCII value is co-prime with k in C++

In this tutorial, we will be discussing a program to convert all lowercase characters to uppercase whose ASCII value is co-prime with k.

For this we will be provided with a string and an integer value k. Our task is to traverse through the given string and change to uppercase all those characters whose ASCII value is co-prime with the given integer k.

## Example

Live Demo

#include <bits/stdc++.h>
using namespace std;
//modifying the given string
void convert_string(string s, int k){
int l = s.length();
for (int i = 0; i < l; i++) {
int ascii = (int)s[i];
//checking if the value is coprime with k
if (ascii >= 'a' && ascii <= 'z'&& __gcd(ascii, k) == 1) {
char c = s[i] - 32;
s[i] = c;
}
}
cout << s << "\n";
}
int main(){
string s = "tutorialspoint";
int k = 3;
convert_string(s, k);
return 0;
}

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