Log Message Timestamp

#include <iostream>
#include <string>
using namespace std;

// Write your function here
void logMessage(string msg,bool flag=false){
    if(flag) printf("[123456] ");
    printf("%s",msg.c_str());
}
int main() {
    int mode;
    string msg;
    cin >> mode >> msg;

    if (mode == 0) {
        logMessage(msg);            // use default argument
    } else {
        logMessage(msg, true);      // enable timestamp
    }

    return 0;
}

Solving Approach