Golang

package main

import (
  "flag"
  "fmt"
)

func main() {
  var L int
  flag.IntVar(&L, "n", 1000, "Number of Pi")
  flag.Parse()

  N := (L)/4 + 1

  s := make([]int, N+3)
  w := make([]int, N+3)
  v := make([]int, N+3)
  q := make([]int, N+3)
  n := (int)(float32(L)/1.39793 + 1)

  w[0] = 16 * 5
  v[0] = 4 * 239

  for k := 1; k <= n; k++ {
    div(w, 25, w, N)
    div(v, 57121, v, N)
    sub(w, v, q, N)
    div(q, 2*k-1, q, N)
    if k%2 != 0 {
      add(s, q, s, N)
    } else {
      sub(s, q, s, N)
    }
  }
  fmt.Printf("%d.", s[0])
  for k := 1; k < N; k++ {
    fmt.Printf("%04d", s[k])
  }
  fmt.Println()
  return
}

func add(a []int, b []int, c []int, N int) {
  i, carry := 0, 0
  for i = N + 1; i >= 0; i-- {
    c[i] = a[i] + b[i] + carry
    if c[i] < 10000 {
      carry = 0
    } else {
      c[i] = c[i] - 10000
      carry = 1
    }
  }
}

func sub(a []int, b []int, c []int, N int) {
  i, borrow := 0, 0
  for i = N + 1; i >= 0; i-- {
    c[i] = a[i] - b[i] - borrow
    if c[i] >= 0 {
      borrow = 0
    } else {
      c[i] = c[i] + 10000
      borrow = 1
    }
  }
}

func div(a []int, b int, c []int, N int) {
  i, tmp, remain := 0, 0, 0
  for i = 0; i <= N+1; i++ {
    tmp = a[i] + remain
    c[i] = tmp / b
    remain = (tmp % b) * 10000
  }
}


Java 

public class Pi {

  public static void main(String[] args) {
    int L = 10000;
    if (args.length == 1) {
      L = Integer.parseInt(args[0]);
    }
    int N = L / 4 + 1;

    int[] s = new int[N + 3];
    int[] w = new int[N + 3];
    int[] v = new int[N + 3];
    int[] q = new int[N + 3];
    int n = (int) (L / 1.39793 + 1);
    int k;

    w[0] = 16 * 5;
    v[0] = 4 * 239;

    for (k = 1; k <= n; k++) {
      div(w, 25, w, N);
      div(v, 57121, v, N);
      // div ( v, 239, v );
      sub(w, v, q, N);
      div(q, 2 * k - 1, q, N);

      if (k % 2 != 0)
        add(s, q, s, N);
      else
        sub(s, q, s, N);
    }

    System.out.printf("%d.", s[0]);
    for (k = 1; k < N; k++) {
      System.out.print(String.format("%04d", s[k]));
      // System.out.printf("%d", s[k]);
    }
    System.out.println();
    return;
  }

  public static void add(int[] a, int[] b, int[] c, int N) {
    int i, carry = 0;
    for (i = N + 1; i >= 0; i--) {
      c[i] = a[i] + b[i] + carry;
      if (c[i] < 10000) {
        carry = 0;
      } else {
        c[i] = c[i] - 10000;
        carry = 1;
      }
    }
  }

  public static void sub(int[] a, int[] b, int[] c, int N) {
    int i, borrow = 0;
    for (i = N + 1; i >= 0; i--) {
      c[i] = a[i] - b[i] - borrow;
      if (c[i] >= 0)
        borrow = 0;
      else {
        c[i] = c[i] + 10000;
        borrow = 1;
      }
    }
  }

  public static void div(int[] a, int b, int[] c, int N) {
    int i, tmp, remain = 0;
    for (i = 0; i <= N + 1; i++) {
      tmp = a[i] + remain;
      c[i] = tmp / b;
      remain = (tmp % b) * 10000;
    }
  }

}


C（代码来自互联网） 

#include <stdio.h>
#define L 10000 //姹?0000浣峆I鍊?
#define N L/4+1

// L 涓轰綅鏁帮紝N鏄痑rray闀垮害

/*鍦嗗懆鐜囧悗鐨勫皬鏁颁綅鏁版槸鏃犳澧冪殑锛屽浣曚娇鐢ㄧ數鑴戞潵璁＄畻杩欐棤姝㈠鐨勫皬鏁版槸涓€浜涙暟瀛﹀涓庣▼寮忚璁″笀鎵€鎰熷叴瓒ｇ殑锛屽湪杩欒竟浠嬬粛涓€涓叕寮忛厤鍚?澶ф暟杩愮畻锛屽彲浠ヨ绠楁寚瀹氫綅鏁扮殑鍦嗗懆鐜囥€?

J.Marchin鐨勫渾鍛ㄧ巼鍏紡锛?
PI = [16/5 - 16 / (3*53) + 16 / (5*55) - 16 / (7*57) + ......] -  [4/239 - 4/(3*2393) + 4/(5*2395) - 4/(7*2397) + ......]

*/
void add ( int*, int*, int* );
void sub ( int*, int*, int* );
void div ( int*, int, int* );

int main ( void )
{
    int s[N+3] = {0};
    int w[N+3] = {0};
    int v[N+3] = {0};
    int q[N+3] = {0};
    int n = ( int ) ( L/1.39793 + 1 );
    int k;

    w[0] = 16*5;
    v[0] = 4*239;

    for ( k = 1; k <= n; k++ )
    {
        // 濂楃敤鍏紡
        div ( w, 25, w );
        div ( v, 57121, v );
        // div ( v, 239, v );
        sub ( w, v, q );
        div ( q, 2*k-1, q );

        if ( k%2 ) // 濂囨暟椤?
            add ( s, q, s );
        else    // 鍋舵暟椤?
            sub ( s, q, s );
    }

    printf ( "%d.", s[0] );
    for ( k = 1; k < N; k++ )
        printf ( "%04d", s[k] );
    printf ( "\n" );
    return 0;
}

void add ( int *a, int *b, int *c )
{
    int i, carry = 0;

    for ( i = N+1; i >= 0; i-- )
    {
        c[i] = a[i] + b[i] + carry;
        if ( c[i] < 10000 )
            carry = 0;
        else   // 杩涗綅
        {
            c[i] = c[i] - 10000;
            carry = 1;
        }
    }
}

void sub ( int *a, int *b, int *c )
{
    int i, borrow = 0;
    for ( i = N+1; i >= 0; i-- )
    {
        c[i] = a[i] - b[i] - borrow;
        if ( c[i] >= 0 )
            borrow = 0;
        else   // 鍊熶綅
        {
            c[i] = c[i] + 10000;
            borrow = 1;
        }
    }
}

void div ( int *a, int b, int *c ) // b 涓洪櫎鏁?
{
    int i, tmp, remain = 0;
    for ( i = 0; i <= N+1; i++ )
    {
        tmp = a[i] + remain;
        c[i] = tmp / b;
        remain = ( tmp % b ) * 10000;
    }
}


性能对比（仅供参考，娱乐使用~）

多种语言计算圆周率_i++