各种编程语言实现 2 + 2 = 5

今天在stackexchange上看到一篇非常有趣的帖子，是关于如何用各种编程语言实现 2 + 2 = 5 的，2 + 2怎么会等于5呢？我一开始也很不解，不过看了下面各种编程语言实现的方法，我震惊了，让我又一次相信人类真是一种不可思议的生物。

1、JAVA

import java.lang.reflect.Field;

public class Main {
public static void main(String[] args) throws Exception {
Class cache = Integer.class.getDeclaredClasses()[0];
Field c = cache.getDeclaredField(“cache”);
c.setAccessible(true);
Integer[] array = (Integer[]) c.get(cache);
array[132] = array[133];

System.out.printf(“%d”,2 + 2);
}
}

输出：

5

2、C

int main() {
char __func_version__[] = “5″; // For source control
char b[]=”2″, a=2;
printf(“%d + %s = %s\n”, a, b, a+b);
return 0;
}

3、C (Linux, gcc 4.7.3)

#include <stdio.h>

int main(void)
{
int a=3, b=2;

printf(“%d + %d = %d”, –a, b, a+b);
}

4、Haskell

λ> let 2+2=5 in 2+2
5

5、BBC BASIC

MODE 6
VDU 23,52,254,192,252,6,6,198,124,0
PRINT
PRINT “2+2=”;2+2
PRINT “2+3=”;2+3

6、Python

>>> patch = ‘\x312\x2D7′
>>> import ctypes;ctypes.c_int8.from_address(id(len(patch))+8).value=eval(patch)
>>> 2 + 2
5

7、JavaScript

g = function () {
H = 3
return H + H
}

f = function () {
Η = 2
return Η + H
}

// 3 + 3 = 6
alert(g())
// 2 + 2 = 5
alert(f())

8、Bash

v=2 #v is 2
v+=2 #v is 4
v=$(($v*5)) #v is 20
v=$(($v-16)) #v is 4
v=$(bc<<<”sqrt($v)+2″) #v is 4 (sqrt(4) is 2)
v=$(bc<<<”$v/4+3″) #v is 4 (4/4 = 1)
echo ’2+2=’ $v #So v is 4…?

9、PHP

echo ’2 + 2 = ‘ . (2 + 2 === 4 ? 4 : 2 + 2 === 5 ? 5 : ‘dunno’);

10、Perl

# Generic includes
use strict;
use warnings;
use 5.010;
use Acme::NewMath;

# Ok, time to begin the real program.
if (2 + 2 == 5) {
say 5;
}
else {
say “Dunno…”;
}

11、C#

static void Main(string[] args)
{
var x = 2;
var y = 2;

if (1 == 0) ;
{
++x;
}

Console.WriteLine(x + y);
}

12、C++

#include <iostream>

class Int
{
public:
Int(const int& a) : integ(a) {}

friend std::ostream& operator<<(std::ostream& oss, const Int& rhs)
{
return oss << rhs.integ;
}
int operator+(Int o)
{
if(integ == 2 && o.integ == 2)
return integ+o.integ+1;
return integ+o.integ;
}

private:
int integ;
};

int main()
{
Int two = 2;
std::cout << two << ” + ” << two << ” = ” << two + two;
}