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

使用std::string::compare:比较最后n个字符:

#include <iostream>

bool hasEnding (std::string const &fullString, std::string const &ending) {
    if (fullString.length() >= ending.length()) {
        return (0 == fullString.compare (fullString.length() - ending.length(), ending.length(), ending));
    } else {
        return false;
    }
}

int main () {
    std::string test1 = "binary";
    std::string test2 = "unary";
    std::string test3 = "tertiary";
    std::string test4 = "ry";
    std::string ending = "nary";

    std::cout << hasEnding (test1, ending) << std::endl;
    std::cout << hasEnding (test2, ending) << std::endl;
    std::cout << hasEnding (test3, ending) << std::endl;
    std::cout << hasEnding (test4, ending) << std::endl;

    return 0;
}

其他回答

检查str是否有后缀,使用如下:

/*
Check string is end with extension/suffix
*/
int strEndWith(char* str, const char* suffix)
{
  size_t strLen = strlen(str);
  size_t suffixLen = strlen(suffix);
  if (suffixLen <= strLen) {
    return strncmp(str + strLen - suffixLen, suffix, suffixLen) == 0;
  }
  return 0;
}

我的观点是:

bool endsWith(std::string str, std::string suffix)
{
   return str.find(suffix, str.size() - suffix.size()) != string::npos;
}
bool endswith(const std::string &str, const std::string &suffix)
{
    string::size_type totalSize = str.size();
    string::size_type suffixSize = suffix.size();

    if(totalSize < suffixSize) {
        return false;
    }

    return str.compare(totalSize - suffixSize, suffixSize, suffix) == 0;
}

另一种选择是使用正则表达式。下面的代码使搜索对大小写不敏感:

bool endsWithIgnoreCase(const std::string& str, const std::string& suffix) {
  return std::regex_search(str,
     std::regex(std::string(suffix) + "$", std::regex_constants::icase));
}

可能不是很有效,但是很容易实现。

使用boost::algorithm::ends_with(参见http://www.boost.org/doc/libs/1_34_0/doc/html/boost/algorithm/ends_with.html):

#include <boost/algorithm/string/predicate.hpp>

// works with const char* 
assert(boost::algorithm::ends_with("mystring", "ing"));

// also works with std::string
std::string haystack("mystring");
std::string needle("ing");
assert(boost::algorithm::ends_with(haystack, needle));

std::string haystack2("ng");
assert(! boost::algorithm::ends_with(haystack2, needle));