Library Function Math.h sqrt()

Library Function Math.h sqrt() in C Language

Library Function Math.h sqrt() function is a mathematical function that is used to calculate the square root  of a number. In C language, to use sqrt( ) we must include math.h header file. Here is the theory of how the library function sqrt() in C is used.

Library Function Math.h sqrt()

C Library Function Math.h sqrt()

In C, the sqrt() function is used to compute the square root of a number. Square root of a number is a value, which on multiplication by itself, gives the original number.

The sqrt() function is declared in the math.h header file, so you’ll need to include that in your program in order to use the sqrt() function.

Syntax for sqrt( ):

double sqrt(double x);

sqrt() function return a double data type as result or as a square root of a number.,


  • Declare an integer variable, as num.
  • Use the sqrt() function to pass the num variable as an argument to find the square root.
  • Print the result.
  • Exit or terminate the program.

Program 1:

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

int main ()
  double a = 81, sq_rt;

  sq_rt = sqrt (a);

  printf ("Square root of %.2lf =  %.2lf", a, sq_rt);

  return 0;


Square root of 81.00 =  9.00

Program 2:


int main ()

  int a = 16, sqr_a;
  float b = 12.25, sqr_b;
  double c = 1443.76;
  sqr_a = sqrt (a);
  sqr_b = sqrt (b);

  printf ("The square root of %d: %d\n", a, sqr_a);
  printf ("The square root of %.2f: %.2f\n", b, sqr_b);
  printf ("The square root of %.4lf: %.4lf\n", c, sqrt (c));

  return 0;


The square root of 16: 4
The square root of 12.25: 3.50
The square root of 1443.7600: 37.9968

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