3种C语言指针交换

#include
void swap(int **m,int **n){//二级指针交换 
	int *i;
	i=*m;
	*m=*n;
	*n=i;
}
void swap2(int &n,int &m){//地址引用交换 
	int t;
	t=n;
	n=m;
	m=t;
}
void swap3(int *n,int *m){//一级指针交换 
	int temp=*n;
	*n=*m;
	*m=temp;
} 
int main(){
	int a,b,*pa,*pb;
	pa=&a;
	pb=&b;
	scanf("%d%d",pa,pb);
	swap(&pa,&pb);//交换了指针*pa，*pb的指向，a,b的值未改变 
	printf("n1:............n");
	printf("a=%d,b=%dn",*pa,*pb);
	printf("a=%d,b=%d",a,b);
	 
	printf("n2:............n");
	swap2(a,b);// 
	printf("a=%d,b=%dn",a,b);
	printf("a=%d,b=%dn",a,b);
	printf("n3..............n");
	swap3(&a,&b);
	printf("a=%d,b=%dn",a,b);
	printf("a=%d,b=%dn",a,b);
	return 0;
}

输入
20 40
运行结果

1:…
a=40,b=20
a=20,b=40
2:…
a=40,b=20
a=40,b=20

3…
a=20,b=40