Three ways to pass parameters to a function

Three ways to pass function parameters

1. Pass by value. When passing, the formal parameters and actual parameters each occupy an independent space.

2. Address transfer is to transfer the storage address of the actual parameter to the formal parameter.

3. Passing by reference is an alias with a reference as the actual parameter, which is the same variable as the actual parameter.

Sample code

Pass by value

#include<stdio.h>
void swap1(int x, int y)//定义中的x,y变量是swap函数的两个形参
{
	int tmp;
	tmp = x;
	x = y;
	y = tmp;
	printf("x=%d,y=%d\n", x, y);
}
int main()
{
	int a = 2;
	int b = 3;
	swap1(a, b);//a,b变量为swap函数的实际参数
	printf("a=%d,b=%d", a, b);
	return 0;
}

Pass by address

void swap2(int *px, int *py)
{
	int tmp;
	tmp = *px;
	*px = *py;
	*py = tmp;
	printf("px=%d,py=%d\n", *px, *py);
}
int main()
{
	int a = 2;
	int b = 3;
	swap2(&a, &b);/*调用了swap函数，同样也有隐含动作px=&a;py=&b;*/
	printf("a=%d,b=%d", a, b);
	return 0;
}

Pass by reference

#include<stdio.h>
void  swap3(int &x,int &y)
{
	int tmp = x;
	x = y;
	y = tmp;
	printf("x=%d,y=%d\n", x, y);
}
int main()
{
	int a = 2;
	int b = 3;
	swap3(a, b);//调用方式与传值一样
	printf("a=%d,b=%d", a, b);
	system("pause");
	return 0;
}

Recommended tutorial ：《C# tutorial》

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