# C Program to Calculate Square Root of a Positive Number

By | June 29, 2019

Q: Write a C Program to Calculate Square Root of a Positive Number

### How To Calculate Square Root of a number in C Programming

We use built-in function sqrt() to calculate square root of a number.

C Program to find square root of positive number

### Include Header File math.h for sqrt() function

We must include math.h header file with the help of pre processor directive in the program. sqrt() function is defined in math.h header file.

#### Source Code for C Program to Find Square root of a number

```/*Input a positive number.
Find square root of this number
*/
#include<stdio.h>
#include<math.h>
int main()
{
double num;
printf("Enter a positive number to find Square Root:");
scanf("%lf",&num);
if(num>0)
printf("Square root of %.2lf is = %.2lf",num, sqrt(num));
return 0;
}
```
Explanation of Logic of this Program
In summary, the program prompts the user to enter a positive number, calculates its square root using the `sqrt` function from the `math.h` library, and displays the result if the input is valid.
1. The program includes the necessary header files: `stdio.h` for input/output operations and `math.h` for mathematical functions.
2. The `main` function is defined as the entry point of the program.
3. Inside the `main` function, a variable `num` of type `double` is declared to store the input number.
4. The `printf` function is used to display a prompt message asking the user to enter a positive number to find its square root.
5. The `scanf` function is used to read a double-precision floating-point number from the user and store it in the `num` variable.
1. An `if` condition is used to check if the entered number `num` is greater than 0, ensuring it is positive.
2. If the condition is true, the `printf` function is used to display the square root of the number. The `%lf` format specifier is used to print the value of `num` and `sqrt(num)` with two decimal places.
3. The `sqrt` function from the `math.h` library is used to calculate the square root of `num`.
4. If the entered number is not positive, the program will skip the `printf` statement, and no output will be displayed.
1. The `return 0;` is the last statement that indicates the successful termination of the `main` function and the program.