find if string endswith another string c++

Question

How to find if string endswith another string c++

Answer 1

Let a be a string and b the string you look for. Use a.substr to get the last n characters of a and compare them to b (where n is the length of b)

Or use 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());
}

Answer 2

Simply compare the last n characters using std::string::compare:

#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;
}

Answer 3

you can use string::rfind

The full Example based on comments:

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;
}

Answer 4

The std::mismatch method can serve this purpose when used to backwards iterate from the end of both strings:

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() );

Answer 5

If you want to ignore '\n' and '\r' at the end of the string, you could modify jcs' solution as follows:

#include <iostream>

bool hasEnding (std::string const &fullString, std::string const &ending)
{
    unsigned int lastMatchPos = fullString.rfind(ending); // Find the last occurrence of ending
    bool isEnding = lastMatchPos != std::string::npos; // Make sure it's found at least once

    // If the string was found, make sure that any characters that follow it are the ones we're trying to ignore
    for( int i = lastMatchPos + ending.length(); (i < fullString.length()) && isEnding; i++)
    {
        if( (fullString[i] != '\n') &&
            (fullString[i] != '\r') )
        {
            isEnding = false;
        }
    }

    return isEnding;
}

int _tmain(int argc, _TCHAR* argv[])
{
    std::string test1 = "binary";
    std::string test2 = "unary\n\r";
    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;

    getchar();

    return 0;
}

Answer 6

what about:

if (std::equal(suffix.rbegin(), suffix.rend(), str.rbegin())
{
    //ends with....
}
else
{
    //does not end with...
}