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，此時a的值為1
        b = a ^ b; // 0001 ^ 0100 ===> 0101，此時b的值為5
        a = a ^ b; // 0001 ^ 0101 ===> 0100，此時a的值為4
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }

//利用php spl標準類庫中的棧數(shù)據(jù)結構，先進后出實現(xiàn)
$a = 'abcde';
$b = 'efghi';

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

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

//利用坐標軸上的兩點距離數(shù)學計算?
$a = 10;
$b = 12;
$a = $b - $a;
$b = $b - $a;//10
$a ?= $b + $a;//12

//利用位運算中的^
$a = 10;
$b = 12;
$a = $a ^ $b;
$b = $b ^ $a; //10
$a = $a ^ $b; //12