Commafy()

Given a number, convert it to a string and put commas in it after every 3 digits. So given a number say 100054, function should return 100,054 or for a number like 3040005, function should return 3,040,005.
The key steps in writing an commafy function are:

• Check if number is 0. In this case return string "0".
• Check if number is less than zero. Save this information in a variable and make the number positive.
• Extract each digit from the number and add a comma after every 3 digits.
• Make sure to append '-' sign before returning result if the number was negative.
• Remember to reverse the string before returning as we extracted digits LSB first and hence generated string is reverse of expected

const char* commafy(int num)
{
    char *text = new char(10);

    //Check for num == 0
    if(num==0)
        return "0\0";

    int i=0, sign = 1, count = 0;
    
    //Check if number < 0, Save this info in variable sign and make the number positive
    if(num<0)
    {
        sign = -1;
        num = num*-1;
    }
    
    //Extract each digit from right and add comma after every 3 digits.
    while(num>0)
    {
        count++;
        if(count >1 && (count%3 ==1))
        text[i++] = ',';
        
        text[i++] = '0' + num%10;
        num=num/10;
        
    }
    
    //Add '-' if number was negative.
    if(sign == -1)
        text[i++] = '-';
    
    //Add null terminator
    text[i] = '\0';
   
    //Reverse string before returning 
    int len = strlen(text);
    for(int i=0;i<(len/2);i++)
    {
        char temp = text[i];
        text[i] = text[len-i-1];
        text[len-i-1] = temp;
    }
    
    return text;
}