add delimiter into string

#include <iostream>#include <string>using namespace std;string formatString(const string& str, int segWidth, char delimiter){    size_t size = str.size();    size_t pos = 0;    string result;    if (size > 0 && segWidth > 0 && size > segWidth) {        while(pos < size) {            result += str.substr(pos, segWidth);            pos += segWidth;            if (pos < size) {                result += delimiter;            }            //cout << result<<endl;        }    }    else {        result = str;    }    return result;}int main(int argc, char* argv[]){    string s1 = "a3dfae18d0dba9027e56591122f3ef84";    string s2 = formatString(s1, 4, '-');    cout << "s1: " << s1 << "\ns2: " << s2<<endl;    return 0;}

output:

s1: a3dfae18d0dba9027e56591122f3ef84
s2: a3df-ae18-d0db-a902-7e56-5911-22f3-ef84