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

我知道这个问题是针对c++的,但如果有人需要一个很好的老式C函数来做到这一点:


/*  returns 1 iff str ends with suffix  */
int str_ends_with(const char * str, const char * suffix) {

  if( str == NULL || suffix == NULL )
    return 0;

  size_t str_len = strlen(str);
  size_t suffix_len = strlen(suffix);

  if(suffix_len > str_len)
    return 0;

  return 0 == strncmp( str + str_len - suffix_len, suffix, suffix_len );
}

其他回答

设a是一个字符串,b是你要找的字符串。使用a.s ustr获取a的最后n个字符,并将它们与b进行比较(其中n是b的长度)

或者使用std::equal (include <algorithm>)

Ex:

bool EndsWith(const string& a, const string& b) {
    if (b.size() > a.size()) return false;
    return std::equal(a.begin() + a.size() - b.size(), a.end(), b.begin());
}

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));

找到了类似的"startWith"问题的好答案:

如何检查一个c++ std::string是否以某个字符串开始,并将子字符串转换为int?

你可以采用只搜索字符串的最后一个位置的解决方案:

bool endsWith(const std::string& stack, const std::string& needle) {
    return stack.find(needle, stack.size() - needle.size()) != std::string::npos;
}

这样你可以使它短小、快速、使用标准c++并使其可读。

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;
}

和上面一样,这是我的解

 template<typename TString>
  inline bool starts_with(const TString& str, const TString& start) {
    if (start.size() > str.size()) return false;
    return str.compare(0, start.size(), start) == 0;
  }
  template<typename TString>
  inline bool ends_with(const TString& str, const TString& end) {
    if (end.size() > str.size()) return false;
    return std::equal(end.rbegin(), end.rend(), str.rbegin());
  }