envlist.c - System Environment Variable Names And Addresses

/**
 * [envlist.c]
 * The console output of a list of a system's environment variables, and the corresponding memory
 * addresses where they are stored.
 *
 *      (c) Damion 'Phr0z3n.dev' Tapper, 2015.
 *      Email: Phr0z3n.Dev@Gmail.com
 *      Website: http://L337Stuff.Blogspot.com
 */

#include <stdio.h>
#include <stdlib.h>

/**
 * main() is implemented with the 'envp' argument variable that will point to the system's environment
 * variables.
 */
int main(int argc, char *argv[], char **envp)
{
    int     i;                                                  /* Primary increment. */
    int     j;                                                  /* Secondary increment. */

    /**
     * Create a buffer that will store the name (only) of each environment variable, and allocate
     * space for it in memory at the same time:
     */
    char    *envBuff = (char *)malloc(100);

        /**
         * Traverse the environment variables pointer array (until a null value is reached):
         */
        for(i = 0; envp[i] != '\0'; i++)
        {
                /**
                 * Copy the name (only) of each environment variable into the buffer:
                 */
                for(j = 0; envp[i][j] != '='; j++)
                    envBuff[j] = envp[i][j];

            /**
             * Terminate the name of the environment variable with the null character:
             */
            envBuff[j] = '\0';

            /**
             * Print out the name of the environment variable, and the corresponding memory address
             * where it is located:
             */
            printf("%s is at %p\n", envBuff, getenv(envBuff));
        }

    /**
     * Delete the buffer from memory, being that it's done with:
     */
    free(envBuff);

    return 0;
}