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