printf的，wprintf％S％S，％LS，char *与WCHAR *：错误不是由编译器警告公布？ [英] printf, wprintf, %s, %S, %ls, char* and wchar*: Errors not announced by a compiler warning?

问题描述

我曾尝试以下code：

  wprintf（L1％S \\ n，一些字符串）; //好
wprintf（L2％S \\ n，L一些字符串）; //不好 - ＆GT;打印字符串只有第一个字符
的printf（3％S \\ n，一些字符串）; //好
//输出（4％S \\ n，L一些字符串）; //不能编译
的printf（\\ n）;
wprintf（L1％S \\ n，一些字符串）; //不好 - ＆GT;打印一些有趣的东西
wprintf（L2％S \\ n，L一些字符串）; //好
//的printf（3％S \\ n，一些字符串）; //不能编译
的printf（4％S \\ n，L一些字符串）; //好
 

和我得到以下的输出：

  1一些字符串
2秒
3一些字符串1 G1％S2一些字符串
4一些字符串
 

所以说：看来这两个 wprintf 和的printf 能够正确打印都一个char *和WCHAR *，但仅在使用的确切说明符。 如果使用了错误的说明，你可能无法得到一个编译错误（也警告！）和错误的行为而告终。您是否遇到相同的行为？

请注意：这是Windows下的测试，与MinGW和编制的 G ++ 4.7.2（我会检查GCC版本）

编辑：我也试过％1！（结果是评论）

 的printf（\\ n）;
wprintf（L1％2！\\ n，一些字符串）; //不好 - ＆GT;打印有趣的东西
wprintf（L2％1！\\ n，L一些字符串）; //好
//输出（3％LS \\ n，一些字符串）; //不能编译
的printf（4％LS \\ n，L一些字符串）; //好
 

解决方案

我怀疑GCC（MinGW的）定制code禁用检查宽的printf 在Windows功能。这是因为微软自己的实现（MSVCRT）是的严重错误的并具有％S 和％1！ 向后作为广的printf 功能;因为GCC不能确定你是否将与MS的破实施或纠正一些之一进行连接，它至少可以做的，突兀的事情只是关闭警告。

I have tried the following code:

wprintf(L"1 %s\n","some string"); //Good
wprintf(L"2 %s\n",L"some string"); //Not good -> print only first character of the string
printf("3 %s\n","some string"); //Good
//printf("4 %s\n",L"some string"); //Doesn't compile
printf("\n");
wprintf(L"1 %S\n","some string"); //Not good -> print some funny stuff
wprintf(L"2 %S\n",L"some string"); //Good
//printf("3 %S\n","some string"); //Doesn't compile
printf("4 %S\n",L"some string");  //Good

And I get the following output:

1 some string
2 s
3 some string

1 g1 %s

2 some string
4 some string

So: it seems that both wprintf and printf are able to print correctly both a char* and a wchar*, but only if the exact specifier is used. If the wrong specifier is used, you might not get a compiling error (nor warning!) and end up with wrong behavior. Do you experience the same behaviour?

Note: This was tested under Windows, compiled with MinGW and g++ 4.7.2 (I will check gcc later)

Edit: I also tried %ls (result is in the comments)

printf("\n");
wprintf(L"1 %ls\n","some string"); //Not good -> print funny stuff
wprintf(L"2 %ls\n",L"some string"); //Good
// printf("3 %ls\n","some string"); //Doesn't compile
printf("4 %ls\n",L"some string");  //Good

解决方案

I suspect GCC (mingw) has custom code to disable the checks for the wide printf functions on Windows. This is because Microsoft's own implementation (MSVCRT) is badly wrong and has %s and %ls backwards for the wide printf functions; since GCC can't be sure whether you will be linking with MS's broken implementation or some corrected one, the least-obtrusive thing it can do is just shut off the warning.

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