在JNI中，经常会遇到这种场景:想在一个.h文件中写一些全局变量，然后所有的cpp文件都能够使用。如下有个a.h文件:
/*
* a.h
*
* Created on: 2014-4-16
* Author: Administrator
*/
#ifndef A_H_
#define A_H_
int mAge = 0;
void setAge(int age);
int getAge();
#endif /* A_H_ */
里面很简单，有个变量mAge，两个接口，设置和读取。
下面是a.cpp文件:
/*
* a.cpp
*
* Created on: 2014-4-16
* Author: Administrator
*/
#include "a.h"
void setAge(int age){
mAge = age;
}
int getAge(){
return mAge;
}
然后有个main.cpp文件:
//============================================================================
// Name : Test2.cpp
// Author : yan
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include
#include "a.h"
using namespace std;
int main() {
cout << "!!!Hello World!!!" << endl; // prints !!!Hello World!!!
setAge(22);
cout<<"age = "<
编译后报错:
E:\WorkSpaces\Eclipse_MinGW_C\Test2\Debug/../src/Test2.cpp:12: multiple definition of `main'
src\main.o:E:\WorkSpaces\Eclipse_MinGW_C\Test2\Debug/../src/main.cpp:13: first defined here
collect2.exe: error: ld returned 1 exit status
Build error occurred, build is stopped
报multiple definition of的错误，解决方法是将变量搞成static。搞成static确实不报错了，但这里却隐藏着一个天大的陷阱：
main.cpp如下:
#include
#include "a.h"
using namespace std;
int main() {
cout << "!!!Hello World!!!" << endl; // prints !!!Hello World!!!
setAge(22);
cout<<"age = "<
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