【C学习】swap函数的多种实现对比

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#include <stdio.h>#include <stdlib.h>void Swap0( int a, int b);//交换函数void Swap1( int *a, int *b);void Swap2( int *a, int *b);void Swap3( int *a, int *b);void Swap4( int *a, int *b);void Swap5( int *a, int *b);int main(){    int a = 2,b = 3;    printf("交换之前:a:%d,b:%d\n",a,b);    Swap0(a,b);    printf("Swap0:a:%d,b:%d\n",a,b);    a = 2,b = 3;    printf("\n交换之前:a:%d,b:%d\n",a,b);    Swap1(&a,&b);    printf("Swap1:a:%d,b:%d\n",a,b);    a = 2,b = 3;    printf("\n交换之前:a:%d,b:%d\n",a,b);    Swap2(&a,&b);    printf("Swap2:a:%d,b:%d\n",a,b);    a = 2,b = 3;    printf("\n交换之前:a:%d,b:%d\n",a,b);    Swap3(&a,&b);    printf("Swap3:a:%d,b:%d\n",a,b);    a = 2,b = 3;    printf("\n交换之前:a:%d,b:%d\n",a,b);    Swap4(&a,&b);    printf("Swap4:a:%d,b:%d\n",a,b);    printf("\n交换之前:a:%d,b:%d\n",a,b);    Swap5(&a,&b);    printf("Swap5:a:%d,b:%d\n",a,b);    return 0;}/*不能交换，形参传值，实际传过去是拷贝的一份，没改变主函数中x,y是值传递:是指在调用函数时将实际参数复制一份传递到函数中，这样在函数中如果对参数进行修改，将不会影响到实际参数。*/void Swap0( int a, int b){int temp;temp = a;a = b;b = temp;    printf("Swap0内，交换后:a:%d,b:%d\n",a,b);}/*不能交换因为形参是指针，所以函数调用要传递变量的地址函数swap1(&a,&b)，形参传递的是的a、b的地址，函数交换了地址。但是地址里存储什么内容没有变。对于main中的a,b值，a是所声明的地址命名，所以a的实际内容也没有变*/void Swap1( int *a, int *b){int *temp;temp = a;    a = b;    b = temp;    printf("Swap1内，交换后:a:%d,b:%d\n",*a,*b);}/*能交换地址指向的内容进行了交换*/void Swap2( int *a, int *b){int temp;temp = *a;    *a = *b;    *b = temp;    printf("Swap2内，交换后:a:%d,b:%d\n",*a,*b);}/*能交换用^是位异或运算，同为0或者同为1时，对应位结果为0；否则为1不使用多余空间最优算法。适合各种情况*/void Swap3( int *a, int *b){    if( *a != *b )    {        *a ^= *b;        *b ^= *a;        *a ^= *b;    }    printf("Swap3内，交换后:a:%d,b:%d\n",*a,*b);}/*能交换用+-运算不使用多余空间缺点：a、b同号时会溢出。改进：swap5、swap3*/void Swap4( int *a, int *b){    if( *a != *b )    {        *a += *b;//a=1,b=2;a+=b为a=3,b=2        *b = *a - *b;//b = a-b=1,a=3        *a -= *b;//a = a-b;    }    printf("Swap4内，交换后:a:%d,b:%d\n",*a,*b);}/*能交换用+-运算不使用多余空间缺点：a、b异号时会溢出。改进：swap4、swap3*/void Swap5( int *a, int *b){    if( *a != *b )    {        *a -= *b;//a=1,b=2;a-=b为a=-1,b=2        *b += *a;//b += a 为b=1,a=-1        *a = *b - *a;//a = b-a;    }    printf("Swap5内，交换后:a:%d,b:%d\n",*a,*b);}
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