strovr

string strovr(int offset, string rep, string source)
// Pass: The offset in the source to overwrite from, the string to overwrite with, the source string
// Return: The string after overwrite
// Assmes: Offset is less than source length
{
	int length = len(source);
	if (length < len(rep) + offset) return left(source, offset) + rep;
	return left(source, offset) + rep + right(source, length - offset - len(rep));
}