C program to find square root of a given number - GeeksforGeeks

13 Apr, 2021
Given a number N, the task is to write a C program to find the square root of the given number N.
Examples: 
Input: N = 12 Output: 3.464102
Input: N = 16 Output: 4 
Method 1: Using inbuilt sqrt() function: The sqrt() function returns the sqrt of any number N.
Below is the implementation of the above approach:
C
// C program for the above approach#include <math.h>#include <stdio.h> // Function to find the square-root of Ndouble findSQRT(double N) { return sqrt(N); } // Driver Codeint main(){     // Given number    int N = 12;     // Function call    printf("%f ", findSQRT(N));    return 0;}
3.464102
 
Method 2: Using Binary Search: This approach is used to find the square root of the given number N with precision upto 5 decimal places. 
The square root of number N lies in range 0 ≤ squareRoot ≤ N. Initialize start = 0 and end = number.Compare the square of the mid integer with the given number. If it is equal to the number, then we found our integral part, else look for the same in the left or right side of mid depending upon the condition.After finding an integral part, we will find the fractional part.Initialize the increment variable by 0.1 and iteratively calculate the fractional part upto 5 decimal places.For each iteration, change increment to 1/10th of its previous value.Finally, return the answer computed.
The square root of number N lies in range 0 ≤ squareRoot ≤ N. Initialize start = 0 and end = number.
Compare the square of the mid integer with the given number. If it is equal to the number, then we found our integral part, else look for the same in the left or right side of mid depending upon the condition.
After finding an integral part, we will find the fractional part.
Initialize the increment variable by 0.1 and iteratively calculate the fractional part upto 5 decimal places.
For each iteration, change increment to 1/10th of its previous value.
Finally, return the answer computed.
Below is the implementation of the above approach:
C
// C program for the above approach#include <stdio.h>#include <stdlib.h> // Function to find the square-root of Nfloat findSQRT(int number){    int start = 0, end = number;    int mid;     // To store the answer    float ans;     // To find integral part of square    // root of number    while (start <= end) {         // Find mid        mid = (start + end) / 2;         // If number is perfect square        // then break        if (mid * mid == number) {            ans = mid;            break;        }         // Increment start if integral        // part lies on right side        // of the mid        if (mid * mid < number) {          //first start value should be added to answer            ans=start;          //then start should be changed            start = mid + 1;        }         // Decrement end if integral part        // lies on the left side of the mid        else {            end = mid - 1;        }    }     // To find the fractional part    // of square root upto 5 decimal    float increment = 0.1;    for (int i = 0; i < 5; i++) {        while (ans * ans <= number) {            ans += increment;        }         // Loop terminates,        // when ans * ans > number        ans = ans - increment;        increment = increment / 10;    }    return ans;} // Driver Codeint main(){     // Given number    int N = 12;     // Function call    printf("%f ", findSQRT(N));    return 0;}
3.464099
 
Method 3: Using log2(): The square-root of a number N can be calculated using log2() as:  
Let d be our answer for input number N, then  
Apply log2() both sides 
Therefore, 
d = pow(2, 0.5*log2(n)) 
Below is the implementation of the above approach:
C
// C program for the above approach#include <math.h>#include <stdio.h> // Function to find the square-root of Ndouble findSQRT(double N) { return pow(2, 0.5 * log2(N)); } // Driver Codeint main(){     // Given number    int N = 12;     // Function call    printf("%f ", findSQRT(N));    return 0;}
3.464102
 
chandrasingh
rahulas1505
muskan98111
root
square-root-decomposition
C Language
C Programs
Mathematical
School Programming
Mathematical
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
Comments
Old Comments
Exception Handling in C++
TCP Server-Client implementation in C
'this' pointer in C++
Input-output system calls in C | Create, Open, Close, Read, Write
Multithreading in C
Strings in C
UDP Server-Client implementation in C
C Program to read contents of Whole File
Header files in C/C++ and its uses
How to return multiple values from a function in C or C++?