Insert function of String in C++

[BSIT07-01]

Here is what I had done in class for Insert Function..
Madam Nay Kaha tha Sahi hay..
But Not Executing here..

#include <iostream>
using namespace std;


void myinsert(char ar1[], char ar2[], int pos)
{
    int n=0;
    char temp[20];

    while(pos<=20)
    {
    
        temp[n]=ar1[pos];
        ar1[pos]=ar2[n];
        pos++;
        n++;
    }
    
    for(int m=0; m<=n; m++)
    {
        ar1[pos]=temp[m];
    }

}


void main()
{
    char myarray1[5]={'1','2','3','4','5'};
    char myarray2[5]={'6','7','8','9','0'};
    int pos=2;

    char newar[20];
    newar=myinsert(myarray1,myarray2,pos);

}