如何在c文件之间共享全局变量？

If i define a global variable in a .c file, how can i use the value of the same variable in another .c file?

如果我在.c文件中定义一个全局变量，我如何在另一个.c文件中使用相同变量的值？

file1.c

在file1.c

#include<stdio.h>

int i=10;

int main()
{
printf("%d",i);
return 0;
}

file2.c

file2.c中

#include<stdio.h>

int main()
{
//some data regarding i
printf("%d",i);
return 0;
}

How can the second file use the value of i from the first file here.

第二个文件如何使用第一个文件中的i值。

7 个解决方案

#1

file 1:

档案1：

int x = 50;

file 2:

文件2：

extern int x;

printf("%d", x);

#2

using extern <variable type> <variable name> in a header or another C file.

在标题或另一个C文件中使用extern 。

#3

Use the extern keyword to declare the variable in the other .c file. E.g.:

使用extern关键字在另一个.c文件中声明该变量。例如。：

extern int counter;

means that the actual storage is located in another file. It can be used for both variables and function prototypes.

表示实际存储位于另一个文件中。它可以用于变量和函数原型。

#4

In the second .c file use extern keyword with the same variable name.

在第二个.c文件中，使用具有相同变量名称的extern关键字。

#5

Do same as you did in file1.c In file2.c:

与在file1.c中执行的操作相同在file2.c中：

#include <stdio.h> 

extern int i;  /*This declare that i is an int variable which is defined in some other file*/

int main(void)
{
/* your code*/

If you use int i; in file2.c under main() then i will be treated as local auto variable not the same as defined in file1.c

如果你使用int i;在main（）下的file2.c中，我将被视为本地自动变量，与file1.c中定义的不同

#6

Use extern keyword in another .c file.

在另一个.c文件中使用extern关键字。

#7

If you want to use global variable i of file1.c in file2.c, then below are the points to remember:

如果你想在file2.c中使用file1.c的全局变量i，那么下面是要记住的要点：

main function shouldn't be there in file2.c
file2.c中不应该包含main函数
now global variable i can be shared with file2.c by two ways:
a) by declaring with extern keyword in file2.c i.e extern int i;
b) by defining the variable i in a header file and including that header file in file2.c.
现在全局变量i可以通过两种方式与file2.c共享：a）通过在file2.c中使用extern关键字声明，即extern int i; b）通过在头文件中定义变量i并在file2.c中包含该头文件。

#1