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closed I need to use the number pi in C. How to enter it?

+3 votes
asked Nov 17, 2021 by xRikishi (150 points)
closed Nov 25, 2021 by Admin
for example y=pi*4?
closed with the note: answered

2 Answers

+3 votes
answered Nov 19, 2021 by Peter Minarik (87,810 points)

Well, you know the value of PI, all you have to do is create either a variable or a macro for it.

#include <stdio.h>

#define PI 3.14159265359f
// float PI = 3.14159265359f; // This would work just as fine

int main()
    float y = PI * 4.0f;
    printf("y = %f\n", y);
    return 0;
commented Nov 19, 2021 by YOU AINT A HACKERR MF (100 points)
i agree with you since you declared the value of PI as a global var it can be used anywhere in the prorgram
+1 vote
answered Nov 24, 2021 by Tg-Tycoon (160 points)

You can also use it directly by adding another library in your code. 

The library is math.h, I will demonstrate it by calculating area of a circle, so it would look like,



int main()


      float r;

      printf("Enter the value of radius of circle\n");


      printf("The area of the circle is %f\n",M_PI*r*r);

      return 0;


      Hope it helps


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