# How to find square root in C++ without using sqrt function?

posted Aug 11

Several ways can find or calculate square roots in C++ programming without using sqrt function. However, to get the answer, several iterations may be required for some large numbers which might appear inconveniencing.

# Methods

1. Log method
2. Power algorithm

## Illustrations

All the methods are explained with illustratoins below.

Log method

Below is one simple log method that can be used:

``````// C++ program to show finding

// square root of a number using log2()

#include<bits/stdc++.h>

double squareRoot(double n)

{

return pow(2, 0.5*log2(n));

}

int main(void)

{

double n = 12;

printf("%lf ", squareRoot(n));

return 0;

} ``````

The declarations of all variables must be made which means the programmer has to specify the value of log and the value of n whose square root needs to be found.

Power algorithm

Below is the power algorithm. The algorithm raises the value of x ^y i.e. x raised to power of y. The power syntax is:

``````#include <math.h>

double pow(double x, double y);``````

Another one

Example of how to find square root using double/ power function is shown below:

``````x = int(input())

import math

print(pow(x, 0.5))

or

print(x**0.5)``````

Note: if the value of x above is negative, the return value is NaN

Hope this helps.

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