C语言中的真与假

最新推荐文章于 2021-05-25 04:52:16 发布

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C语言中在用到循环语句时，我们都会涉及到表达式真假判断，‘真值’有哪些？'假值'有哪些？

我们用代码来实现看看

tf.c                                                                                     
  1 /*********************************************************************************
  2  *      Copyright:  (C) 2018 lingyun
  3  *                  All rights reserved.
  4  *
  5  *       Filename:  tf.c
  6  *    Description:  This file
  7  *                 
  8  *        Version:  1.0.0(07/14/2018)
  9  *         Author:  huangjy <771018493@qq.com>
10  *      ChangeLog:  1, Release initial version on "07/14/2018 02:49:55 PM"
11  *                 
12  ********************************************************************************/
13 #include <stdio.h>
14    
15 int main(void)
16 {  
17     int true_value,false_value;
18    
19     true_value = (2>1);
20     false_value = (2<1);
21    
22     printf("tru = %d, false = %d;\n",true_value,false_value);
23    
24     return 0 ;
25 }  


运行结果：

[a4729821@JYstd c_test]$ gcc tf.c
[a4729821@JYstd c_test]$ ./a.out
tru = 1, false = 0;

trust.c                                                                                  
  2  *      Copyright:  (C) 2018 lingyun
  3  *                  All rights reserved.
  4  *  
  5  *       Filename:  trust.c
  6  *    Description:  This file
  7  *                 
  8  *        Version:  1.0.0(07/14/2018)
  9  *         Author:  huangjy <771018493@qq.com>
10  *      ChangeLog:  1, Release initial version on "07/14/2018 02:34:29 PM"
11  *                 
12  ********************************************************************************/
13 #include <stdio.h>
14     
15 int main(void)
16 {   
17    int n = 4;
18     
19    while(n)
20        printf("%2d is trust;\n",n--);
21     printf("%2d is false;\n",n);
22     
23         n = -4;
24      while(n)
25          printf("%2d is trust;\n",n++);
26      printf("%2d is false;\n",n);
27     
28      return 0;     
29 }   
30     
运行结果：

[a4729821@JYstd c_test]$ gcc trust.c
[a4729821@JYstd c_test]$ ./a.out
4 is trust;
3 is trust;
2 is trust;
1 is trust;
0 is false;
-4 is trust;
-3 is trust;
-2 is trust;
-1 is trust;
0 is false;