getenv函数未返回预期答案

Question

I'm trying to access one of my environement variable, which is JAVA_HOME . To do so, I'm using getenv() function, like this :

#include <iostream>
#include <string.h>

int main() {
    const char* env = getenv("JAVA_HOME");
    if(env != NULL)
        std::cout << "Environnement : " << env << std::endl;
    else
        std::cout << "NULL" << std::endl;
    return 0;
}

I tryed std::getenv("PATH"); which returns me something different from my file /etc/bash.bashrc where I put my JAVA_HOME variable.

I expected std::getenv("JAVA_HOME") to return what I put in my /etc/bash.bashrc file. Now it returns something different.

How can I get a correct environement variable ? What am I doing wrong ?

I'm under Ubuntu 12.04 with GCC 4.7.2 using C++11 with QtCreator

EDIT : Code

• Include[...] was a shorthand for the includes

• Added NULL handling

EDIT : Progress

• I tryed extern char **environ but it doesn't contain the one variable I need ...

EDIT : Partial Solution

There's not way to do such things easily as I found out. I've set personal environment variables in the IDE to overcome the problem.

Answer 1

Your code is fine, except that you should explicitly handle the NULL return value from getenv() .

The issue is almost certainly with how your run the code. If you:

1. start a shell;
2. make sure $JAVA_HOME is set correctly in that shell (through bashrc or whatever other means);
3. run the executable from the shell;

I bet it will work correctly.