c语言 引用调用

Here you will learn about difference between call by value and call by reference in C.

在这里，您将了解C中按值调用和按引用调用之间的区别。

There are two different ways of passing values to functions: call by value and call by reference. They are also called as pass by value and pass by reference.

将值传递给函数的方式有两种：按值调用和按引用调用。 它们也称为按值传递和按引用传递。

在C中按值调用 (Call by Value in C)

In call by value method a copy of actual parameters is passed which is stored in formal parameters.

在按值调用方法中，传递实际参数的副本，该副本存储在形式参数中。

Actual Parameters: The parameters that are passed while calling the function are called actual parameters.

实际参数：调用函数时传递的参数称为实际参数。

Formal Parameters: The parameters that hold the values of actual parameters are called formal parameters.

形式参数：保存实际参数值的参数称为形式参数。

In call by value method, if any changes are done in formal parameters then actual parameters are not changed.

在按值调用方法中，如果对正式参数进行了任何更改，则实际参数不会更改。

Let’s take an example of call by value in C language.

让我们以C语言中的按值调用为例。

Example:

例：

#include<stdio.h>
 
void fun(int x)
{
	x=x+5;
}
 
int main()
{
	int a=10;
	printf("Before calling\na=%d",a);
	fun(a);
	printf("\n\nAfter calling\na=%d",a);
	
	return 0;
}

Output:

输出：

As you can clearly see in output that after calling the function and doing changes in formal parameter x, the actual parameter a is not changed.

如您在输出中清楚看到的那样，在调用函数并对形式参数x进行更改之后，实际参数a不会更改。

在C中通过引用调用 (Call by Reference in C)

In call by reference method, reference or address of actual parameters is passed which is stored in formal parameters.

在按引用调用方法中，将传递实际参数的引用或地址，并将其存储在形式参数中。

If any changes are done in formal parameters then actual parameters are also changed.

如果对形式参数进行了任何更改，则实际参数也会更改。

Let’s take an example of call by reference in C language.

让我们以C语言中的引用调用为例。

Example:

例：

#include<stdio.h>
 
void fun(int *x)
{
	*x=(*x)+5;
}
 
int main()
{
	int a=10;
	printf("Before calling\na=%d",a);
	fun(&a);
	printf("\n\nAfter calling\na=%d",a);
	
	return 0;
}

Output:

输出：

You can clearly see in output that after calling the function and doing changes in formal parameter x, the actual parameter a is also changed.

您可以从输出中清楚地看到，在调用函数并对形式参数x进行更改之后，实际参数a也将更改。

C中按值调用和按引用调用之间的区别 (Difference between Call by Value and Call by Reference in C)

If you have any doubts related to above tutorial then you can ask it by commenting below.

如果您对以上教程有任何疑问，可以在下面评论中提出。

翻译自: https://www.thecrazyprogrammer.com/2015/12/difference-between-call-by-value-and-call-by-reference-in-c.html

c语言 引用调用