Java不借助第三变量实现两数交换的示例

    public void swapOne(){
        int a = 4;
        int b = 5;
        int c = a;
        a = b;
        b = c;
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }

    public void swapTwo(){
        int a = 4;
        int b = 5;
        a=a+b;
        b=a-b;
        a=a-b;
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }

    public void swapThree(){
        int a = 4;
        int b = 5;
        a = a ^ b; // 0101 ^ 0100 ===> 0001，此时a的值为1
        b = a ^ b; // 0001 ^ 0100 ===> 0101，此时b的值为5
        a = a ^ b; // 0001 ^ 0101 ===> 0100，此时a的值为4
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }

//利用php spl标准类库中的栈数据结构，先进后出实现
$a = 'abcde';
$b = 'efghi';

$stack = new SplStack();
$stack->push($a);
$stack->push($b);

$a = $stack->pop();//efghi
$b = $stack->pop();//abcde

//利用坐标轴上的两点距离数学计算 
$a = 10;
$b = 12;
$a = $b - $a;
$b = $b - $a;//10
$a  = $b + $a;//12

//利用位运算中的^
$a = 10;
$b = 12;
$a = $a ^ $b;
$b = $b ^ $a; //10
$a = $a ^ $b; //12