Private: 私有的：extern的用法
bigzhu
posted @ Dec 10, 2007 06:05:00 PM
in cpp
, 1557 阅读
终于明白c 区分声明和定义是为了让同一个变量,让多个文件来访问.
声明只是为了告诉编译器:我要在这里使用这个变量,但是他的定义不在这里,你到include的文件里面去找吧.
//test2.cpp
int x = 100;
int y = 200;
然后在另外一个文件里面,使用这两个变量:
// test.cpp
// extern 範例
#include
#include “test2.cpp” // 定义 x 和 y
int a = 10;
extern int x; // 有效範圍; 整個程式
int main(int argc, char* argv[])
{
extern int y; // 有效範圍: 這個函數內
std::cout << a << std::endl; // 10
std::cout << x << std::endl; // 100
std::cout << y << std::endl; // 200
return 0;
}
Sep 29, 2022 01:21:48 PM
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