StrCmpN BUG?

Question

#include "stdafx.h"
#include <stdio.h>
#include <shlwapi.h>
#pragma   comment(lib, "shlwapi.lib")

int main(int argc, char* argv[])
{
 int id1=StrCmpN ("B","c",1);
 int id2=StrCmpN ("a","A",1);
 int id3=StrCmpN ("c","A",1);
 printf("%d,%d,%d \n",id1,id2,id3);
 return 0;
}

output:

-1,-1,1
Press any key to continue

 XP SP3 VC6/VB6/VS2008

Answer 1

Use strncmp()

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Visual C++ enthusiast, like network programming and driver development. At present is being engaged in the WinCE/Windows Mobile platform embedded development.

Answer 2

你好，

 

StrCmpN(PCTSTR psz1,PCTSTR psz2,int nChar)是判断两个字符串的大小，当字符串相等是返回值是0，当psz1大于psz2时，返回一个正数，当psz1小于psz2时返回一个负数。

我对你的程序做了简单的修改，帮助你解决你的问题。

int BB = 'B';

      int CC = 'c';

      int AA = 'A';

      int a = 'a';

      printf(" BB(B): %d \n CC(c): %d \n AA(A): %d \n a(a): %d",BB,CC,AA,a);

      int id1=StrCmpN  ("B","c",1);

      int id2=StrCmpN  ("a","A",1);

      int id3=StrCmpN  ("c","A",1);

      printf("%d,%d,%d \n",id1,id2,id3);

         return 0;

 

你可以得到这样的结果: BB(B): 66

                 CC(c): 99

                  AA(A): 65

                 a(a): 97

因为StrCmpN在判断单个字符的时候会装换成字符对应的ASC码，因此会出现你所得到的结果。

 

希望我的回答对你的疑问有所帮助

---

Rob Pan [MSFT]
MSDN Community Support | Feedback to us
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Answer 3

感谢 回复 我理解也是按照ASC码比较的,可是按照我的理解
 int id1=StrCmpN ("B","c",1);
 int id2=StrCmpN ("a","A",1);
 int id3=StrCmpN ("c","A",1);
 printf("%d,%d,%d \n",id1,id2,id3);

正确的输出结果应该是 -1,1,1

而不是 -1,-1,1啊!!!

Answer 4

你好，

 

经过我的再次的实验，我也得到了你所得到的结果。我也发现了StrCmpN的排序方式不是按照ASC码来排序的。它是通过字母表顺序来排序的。

例如：StrCmpN ("B","c",1); 正如字母表中的顺序B是在C之后因此，得到的结果是B<C,同理，StrCmpN ("c","A",1); C也大于A。 如果是相同字母在比较是，大写字母A是大于小写字母a。因此StrCmpN ("a","A",1) 得到-1的结果。

 

希望我这次的回答能够解决你的疑问。

---

Rob Pan [MSFT]
MSDN Community Support | Feedback to us
Get or Request Code Sample from Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.