ï»?!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  Cè¯è¨€ä¸çš„预编译包å«ä¸‰¿U:1.å®å®šä¹?.æ–‡äšg包å«3.æ¡äšg¾~–译åQŒæ¡ä»¶ç¼–译指的是满èƒö一定æ¡ä»¶ä¸‹æ‰è¿›è¡Œç¼–è¯‘ï¼Œå®ƒæœ‰å‡ ç§å½¢å¼åQ?/span>
  (1)#ifdefæ ‡è¯†½W?/span>
  //½E‹åº
  #else
  //½E‹åº
  #endif
  它的æ„ä¹‰ä¸ºå¦‚æžœå®šä¹‰äº†æ ‡è¯†½W¦ï¼Œåˆ™æ‰§è¡Œç¨‹åºæ®µ1åQŒå¦åˆ™æ‰§è¡Œç¨‹åºæ®µ2
  或者用以下的åÅžå¼?/span>
  # ifdef æ ‡è¯†½W?/span>
  //½E‹åº
  #endif
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  # include <stdio.h>
  # include <stdlib.h>
  int main()
  {
  #ifdef DEBUG
  printf("debug is running\n");
  #else
  printf("debug is not running\n");
  #endif
  system("pause");
  return 0;
  }
  </stdlib.h></stdio.h>
  (2)
  #ifndef æ ‡è¯†½W?/span>
  //½E‹åº1
  #else
  //½E‹åº2
  #endif
  它的å«ä¹‰æ˜¯å¦‚æžœæ ‡è¯†ç¬¦æ²¡æœ‰è¢«å®šä¹‰ï¼Œåˆ™æ‰§è¡Œç¨‹åºæ®µ1åQŒå¦åˆ™æ‰§è¡Œç¨‹åºæ®µ2
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  # include <stdio.h>
  # include <stdlib.h>
  int main()
  {
  #ifndef DEBUG
  printf("debug is not running\n");
  #else
  printf("debug is running\n");
  #endif
  system("pause");
  return 0;
  }
  </stdlib.h></stdio.h>
  (3)#if表达�/span>
  //½E‹åº1
  #else
  //½E‹åº2
  #endif
  它的æ„义䏸™¡¨è¾‘ּ的å€égؓ真时åQŒå°±¾~–译½E‹åºŒD?åQŒè¡¨è¾‘ּ的å€égØ“å‡æ—¶åQŒå°±¾~–译½E‹åºŒD?
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  # include <stdio.h>
  # include <stdlib.h>
  # define HEX 1
  int main()
  {
  int i=10;
  #if HEX==1
  printf("%x\n",i);
  #else
  printf("%d\n",i);
  #endif
  system("pause");
  return 0;
  }</stdlib.h></stdio.h>