在c++中,如何知道字符串是否以另一个字符串结束?


当前回答

bool EndsWith(const std::string& data, const std::string& suffix)
{
    return data.find(suffix, data.size() - suffix.size()) != std::string::npos;
}

测试

#include <iostream>
int main()
{
   cout << EndsWith(u8"o!hello!1", u8"o!") << endl; 
   cout << EndsWith(u8"o!hello!", u8"o!") << endl; 
   cout << EndsWith(u8"hello!", u8"o!") << endl; 
   cout << EndsWith(u8"o!hello!o!", u8"o!") << endl; 
   return 0;
}

输出

0 
1 
1 
1 

其他回答

std::mismatch方法可以用于从两个字符串的末尾开始向后迭代:

const string sNoFruit = "ThisOneEndsOnNothingMuchFruitLike";
const string sOrange = "ThisOneEndsOnOrange";

const string sPattern = "Orange";

assert( mismatch( sPattern.rbegin(), sPattern.rend(), sNoFruit.rbegin() )
          .first != sPattern.rend() );

assert( mismatch( sPattern.rbegin(), sPattern.rend(), sOrange.rbegin() )
          .first == sPattern.rend() );

使用这个函数:

inline bool ends_with(std::string const & value, std::string const & ending)
{
    if (ending.size() > value.size()) return false;
    return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
}

让我用不区分大小写的版本扩展Joseph的解决方案(在线演示)

#include <string>
#include <cctype>

static bool EndsWithCaseInsensitive(const std::string& value, const std::string& ending) {
    if (ending.size() > value.size()) {
        return false;
    }
    return std::equal(ending.crbegin(), ending.crend(), value.crbegin(),
        [](const unsigned char a, const unsigned char b) {
            return std::tolower(a) == std::tolower(b);
        }
    );
}

你可以使用string::rfind

基于注释的完整示例:

bool EndsWith(string &str, string& key)
{
size_t keylen = key.length();
size_t strlen = str.length();

if(keylen =< strlen)
    return string::npos != str.rfind(key,strlen - keylen, keylen);
else return false;
}

我认为发布一个不使用任何库函数的原始解决方案是有意义的…

// Checks whether `str' ends with `suffix'
bool endsWith(const std::string& str, const std::string& suffix) {
    if (&suffix == &str) return true; // str and suffix are the same string
    if (suffix.length() > str.length()) return false;
    size_t delta = str.length() - suffix.length();
    for (size_t i = 0; i < suffix.length(); ++i) {
        if (suffix[i] != str[delta + i]) return false;
    }
    return true;
}

添加一个简单的std::tolower,我们可以使这种情况不敏感

// Checks whether `str' ends with `suffix' ignoring case
bool endsWithIgnoreCase(const std::string& str, const std::string& suffix) {
    if (&suffix == &str) return true; // str and suffix are the same string
    if (suffix.length() > str.length()) return false;
    size_t delta = str.length() - suffix.length();
    for (size_t i = 0; i < suffix.length(); ++i) {
        if (std::tolower(suffix[i]) != std::tolower(str[delta + i])) return false;
    }
    return true;
}