How to use environment variable in a C program

问题

I need to know a way for use environment variables in the C programming language. How can I use and read them?

For example, read an environment variable or take the value of an environment variable and load it in another variable.

回答1:

You can use following functions -

char * getenv (const char *name)-returns a string that is the value of the environment variable name.

char * secure_getenv (const char *name)

Read about some more functions here -http://www.gnu.org/software/libc/manual/html_node/Environment-Access.html#Environment-Access

回答2:

Use the getenv function. That's it!

回答3:

#include <stdio.h>

int main(int argc, char **argv, char **envp)
{
    char **env;
    for(env = envp; *env != 0; env++)
    {
        char *thisEnv = *env;
        printf("%s\n", thisEnv);
    }
    return 0;
}

thats how you can get those variables

来源：https://stackoverflow.com/questions/31906192/how-to-use-environment-variable-in-a-c-program