用 C 计算 Pi

Question

I want to calculate pi but I am getting 3.058403 as a result. How can I fix this code?

#include <stdio.h>

int main(){
double x = 0;
float g =0;

printf("How many terms to calculate pi to? ");
scanf("%f", &g);

int n;
for (n = 0; n < g ; n++){
  
     double z = 1.0 / (2 * n + 1);
     if ((n % 2) == 1){
        z = z * -1;
     }
     x = (x + z);
     }
     double p = 4 * x;
    printf("The value of pi is: %f", p);
  return 0;
 }

Answer 1

This is not really an answer because the actual answer has been discussed in the comment section.

Corrected version of your code:

• removed pointless parentheses
• use meaningful variable names
• use of int for integer comparison
• declaration of variables as close as possible to their scope
• code formatted properly

#include <stdio.h>

int main() {
  printf("How many terms to calculate pi to? ");

  int nbofterms;
  scanf("%d", &nbofterms);

  double x = 0;

  for (int n = 0; n < nbofterms; n++) {
    double z = 1.0 / (2 * n + 1);
    if (n % 2 == 1) {
      z *= -1;
    }
    x = (x + z);
  }

  double pi = 4 * x;
  printf("The value of pi is: %f", pi);
  return 0;
}