粘贴箱: charexplore.c

格式

C

提交日期

2021-01-19 20:13

Publication Period

Unlimited

 /* A quick program to explore char type.
 ** Joel Rees, January 19, 2020.
 */
 
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 
 int main()
 {
   char guard1[16] = "012345678901234";
   int canary1 = -1; /* On modern compilers, these move. */
   char bullseye = '\0';
   int canary2 = -1;
   char guard2[16] = "012345678901234";
 
   printf( "1st canary starts with %d,\n", canary1 );
   printf( "2nd with %d.\n", canary2 );
   printf( "Bullseye is %d, looks like '%c'.\n",
     bullseye, bullseye );
   printf( "1st guard is \"%s\"\n", guard1 );
   printf( "2nd guard is \"%s\"\n", guard2 );
 
   bullseye = 42;
   printf( "Now bullseye is %d, looks like '%c'.\n",
     bullseye, bullseye );
   printf( "1st canary is still %d,\n", canary1 );
   printf( "2nd is still %d.\n", canary2 );
   printf( "1st guard is still \"%s\"\n", guard1 );
   printf( "2nd guard is still \"%s\"\n", guard2 );
 
   strcpy( &bullseye, "Character?" );
   printf( "After strcpy, bullseye is %d, looks like '%c'.\n",
     bullseye, bullseye );
   printf( "1st canary is now %d,\n", canary1 );
   printf( "2nd is now %d.\n", canary2 );
   printf( "1st guard is now \"%s\"\n", guard1 );
   printf( "2nd guard is now \"%s\"\n", guard2 );
   printf( "Where did we write that string \"%s\"?\n",
     &bullseye ); 
 
   printf( "Clues:\n" );
   printf( "\t&guard1 \t= 0x%lx\n", (unsigned long) &guard1 );
   printf( "\t&canary1\t= 0x%lx\n", (unsigned long) &canary1 );
   printf( "\t&bullseye\t= 0x%lx\n", (unsigned long) &bullseye );
   printf( "\t&canary2\t= 0x%lx\n", (unsigned long) &canary2 );
   printf( "\t&guard2 \t= 0x%lx\n", (unsigned long) &guard2 );
 
   return EXIT_SUCCESS;
 }