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#include <stdio.h>
#include <stdlib.h>
/*
This program is written to demonstrate the <stdlib.h> library.
This program will demonstrate environmental functions of the stdlib library.
Written by James M. Rogers
22 March 1999
Released to the Public Domain on this date.
*/
#define OVERWRITE 1
#define NO_OVERWRITE 0
void shutdown_1 () {
printf("\nShutting down!\n\n");
}
void shutdown_2 () {
printf("\nReally Shutting down!\n\n");
}
void shutdown_3 () {
printf("\nReally Really Shutting down!\n\n");
}
void shutdown_4 () {
printf("\nReally Really Really Shutting down!\n\n");
}
main(){
atexit(shutdown_4);
printf("I am displaying the environmental variable TESTING : ");
printf("%s\n", getenv("TESTING"));
printf("The following setenv will only set TESTING if TESTING is unset : ");
if ( setenv("TESTING", "no_overwite", NO_OVERWRITE) ) {
abort();
} else {
printf("%s\n", getenv("TESTING"));
}
atexit(shutdown_3);
printf("I am unsetting TESTING.\n");
unsetenv("TESTING");
printf("The following setenv will only set TESTING if TESTING is unset : ");
if ( setenv("TESTING", "no_overwite", NO_OVERWRITE) ) {
abort();
} else {
printf("%s\n", getenv("TESTING"));
}
atexit(shutdown_2);
printf("The following setenv will always set TESTING : ");
if ( setenv("TESTING", "overwrite", OVERWRITE) ) {
abort();
} else {
printf("%s\n", getenv("TESTING"));
}
atexit(shutdown_1);
exit (0);
}
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