C# 的字符串的确切模拟是什么。比较忽略 C++ 中的大小写？

Question

Maybe somebody knows, what is exact C/C++ analog of C#'s string.Compare ignoring case? Turned out, that _wcsicmp differs, although both are supposed to use current locale or culture (which is en_US ).

With string.Compare(..., true),
 or string.Compare(..., StringComparison.CurrentCultureIgnoreCase),
 or string.Compare(..., StringComparison.InvariantCultureIgnoreCase):
'~' before '+',
'=' before number,
letter before single quote

_wcsicmp or wcsicmp_l with explicit locale (LC_ALL, L"en_US") puts them in opposite order.

I can reproduce it using character table, but maybe there is a better way. Thanks!

Answer 1

In C there is a function for this in strings.h called strcasecmp() , but it is not portable. Although there is a Windows equivalent as noted in this answer: error C3861: 'strcasecmp': identifier not found in visual studio 2008?

So you could write something like this.

#include <stdio.h>
#include <strings.h>

#ifdef _MSC_VER
//not #if defined(_WIN32) || defined(_WIN64) because we have strncasecmp in mingw
#define strncasecmp _strnicmp
#define strcasecmp _stricmp
#endif

int main () {
    char *str1 = "this is a string";
    char *str2 = "THIS IS A STRING";

    if (strcasecmp(str1, str2) == 0) printf("Strings match\n");

    return 0;
}

If you really wanted, you could use this same approach with C++ strings by using their c_str() function.

strcasecmp(str1.c_str(), str2.c_str())

But really you'd be better off using boost::iequals(str1, str2)

#include <stdio.h>
#include <boost/algorithm/string.hpp>

int main () {
    std::string str1 = "this is a string";
    std::string str2 = "THIS IS A STRING";

    if (boost::iequals(str1, str2)) printf("Strings match\n");

    return 0;
}