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::equal算法从<algorithms>与反向迭代:
std::string LogExt = ".log";
if (std::equal(LogExt.rbegin(), LogExt.rend(), filename.rbegin())) {
…
}
从c++ 20开始引入ends_with。
其他回答
我的观点是:
bool endsWith(std::string str, std::string suffix)
{
return str.find(suffix, str.size() - suffix.size()) != string::npos;
}
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;
}
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);
}
);
}
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));