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HomeTop Coding QuestionC++ program to find the Square root of a number in C++.

# C++ program to find the Square root of a number in C++.

#### find the square root of a number

Given a number we have to find the square root of a number and print the resultant value .

So what is square root of number?

Square root of a number is calculated by mathematically

squareroot(num)=n*n

to solve this problem we have inbuilt library in c++ sqrt() which will make easier to calculate during any test.

Example:

``````input:36
output:6

input:25
output:5``````

Approach 1:Using sqrt function

Code-

```#include<bits/stdc++.h>
using namespace std;
int main() {
int num;
cout<<"Enter a number "<<endl;
cin>>num;
double root=sqrt(num);//this is stl library function.
cout<<root<<endl;

}
```

Approach 2:Without sqrt function

Logic:

``this method is same like binary search,  we will check square root of number between low and high value.``
```#include<bits/stdc++.h>
using namespace std;
int main()
{
cout<<"Enter a number"<<endl;
int num;
cin>>num;
int square;
if(num==0||num==1)
{
square=num;
}
else
{

//lets apply binary search concept here.
int mid=0;
int low=1;
int high=num;
while (low <= high)
{
int mid = (low + high) / 2;
if (mid*mid == num)
{
return mid;
}
if (mid*mid < num)
{
low = mid + 1;
square = mid;
}
else
{
high = mid-1;
}
}

}
cout<<square<<endl;
return 0;
}
```

Output:

```enter a number:16
4```

Time complexity:0(logN)

Space Complexity:O(1)