C++ 中不区分大小写的标准字符串比较
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Case insensitive standard string comparison in C++
提问by Santhosh Kumar
void
main()
{
std::string str1 = "abracadabra";
std::string str2 = "AbRaCaDaBra";
if (!str1.compare(str2)) {
cout << "Compares"
}
}
How can I make this work? Bascially make the above case insensitive. Related question I Googled and here
我怎样才能使这项工作？基本上使上述大小写不敏感。相关问题我在谷歌上搜索过
http://msdn.microsoft.com/en-us/library/zkcaxw5y.aspx
http://msdn.microsoft.com/en-us/library/zkcaxw5y.aspx
there is a case insensitive method String::Compare(str1, str2, Bool). Question is how is that related to the way I am doing.
有一个不区分大小写的方法 String::Compare(str1, str2, Bool)。问题是这与我的工作方式有什么关系。
回答by 0x499602D2
You can create a predicate function and use it in std::equalsto perform the comparison:
您可以创建一个谓词函数并使用它std::equals来执行比较：
bool icompare_pred(unsigned char a, unsigned char b)
{
return std::tolower(a) == std::tolower(b);
}
bool icompare(std::string const& a, std::string const& b)
{
if (a.length()==b.length()) {
return std::equal(b.begin(), b.end(),
a.begin(), icompare_pred);
}
else {
return false;
}
}
Now you can simply do:
现在你可以简单地做：
if (icompare(str1, str)) {
std::cout << "Compares" << std::endl;
}
回答by Andro
Covert both to lower case and then compare them.
将两者都转换为小写，然后比较它们。
Converting to lower:
转换为较低：
for(int i = 0; i < str1.size(); i++)
{
str[i] = tolower(str[i]);
}
Comparing strings:
比较字符串：
if (str1.compare(str2) == 0) { ... }
A zero value indicates that both strings are equal.
零值表示两个字符串相等。
EDIT
编辑
This can be used to avoid for loop: http://www.cplusplus.com/reference/algorithm/transform/
这可以用来避免循环：http: //www.cplusplus.com/reference/algorithm/transform/
std::transform(in.begin(),in.end(),std::back_inserter(out),tolower);
