I am doing c++

Write a function to determine the squareroot of a number. The squareroot of a number can be approximated by repeated calculation using the formula NG = 0.5 (LG + N/LG) where NG stands for the next guess and LG stands for the last guess. The loop should repeat until the difference between NG and LG is less than 0.00001. Use an initial guess of 1.0. Write a driver program to test your squareroot function