sqrt() Function in C

sqrt() function in C is a predefined function in the math.h library used to calculate the square root of a given number. To use this function, we must include the <math.h> header file in our program. It returns the square root of the number as a double and works with double data types, for other data types like float or long double, we can use sqrtf() and sqrtl(), respectively.

Syntax of sqrt() in C

double sqrt(double x);

Parameters of sqrt()

The sqrt(x) function takes a single parameter:

x: A non-negative double value for which the square root is to be calculated that must be a non-negative double.

Return Value of sqrt()

The sqrt(x) function returns the square root of the given number x passed as parameter. If the input is negative, it returns a domain error (NaN) because square root of negative number results in a imaginary number that is not supported by sqrt() function.

Examples of `sqrt()` in C

Input:
double number = 25.0;

Output:
Square root of 25.00 = 5.00

Example 1

The below program demonstrates how we can calculate the square root of a given number using the sqrt(x) function in C.

C++

// C Program to calculate the square root using sqrt()
// function

#include <math.h>
#include <stdio.h>

int main()
{
    // Declare variables to store the input number and its
    // square root
    double number, squareRoot;

    // Prompt the user to enter a number
    printf("Enter a number: ");
    // Read the number entered by the user
    scanf("%lf", &number);

    // Compute the square root of the entered number
    squareRoot = sqrt(number);

    // Print the square root with 2 decimal places
    printf("Square root of %.2lf = %.2lf\n", number,
           squareRoot);

    return 0;
}

Output

Enter a number: 25
Square root of 25.00 = 5.00

Time Complexity: O(1), constant as it performs a single mathematical operation.
Auxiliary Space: O(1)

Example 2

The below example demonstrates how we can calculate square root of different data types in C.

// C program to calculate square root of different data
// types

#include <math.h>
#include <stdio.h>

int main()
{

    // Declare and initialize variables of different types
    // double type variable
    double num1 = 9.0;
    // float type variable
    float num2 = 16.0f;
    // long double type variable
    long double num3 = 25.0l;

    // Compute the square root using the appropriate sqrt
    // function for each type sqrt function for double
    double result1 = sqrt(num1);
    // sqrtf function for float
    float result2 = sqrtf(num2);
    // sqrtl function for long double
    long double result3 = sqrtl(num3);

    // Print the results
    printf("Square root of %.2f is %.2f\n", num1, result1);
    printf("Square root of %.2f is %.2f\n", num2, result2);
    printf("Square root of %.2Lf is %.2Lf\n", num3,
           result3);

    return 0;
}