In this article we will discuss both case sensitive and insensitive implementations to check if a string ends with an another given string.
In previous article we discussed different implementations of startsWith() function for std::string. Here on similar lines we will discuss different implementations of endsWith() function.
In c++, std::string class does not provides any endsWith() function to check if a string ends with an another given string. Let’s see how to do that using std::string::compare() and Boost Library.
std::string endWith() using std::string::compare() and std::all_of()
std::string class provides a member function compare() with different overloaded versions. We will use one of its overloaded version i.e.
int compare (size_t pos, size_t len, const string& str) const;
It accepts a string as argument to match, starting position for match and number of characters to match. If string matches then it returns 0 else returns > 0 or < 0 based on difference in ascii values of first unmatched character.
To check if a main string ends with a given string, we should look into last n characters only for main string, where n is the size of given string. Let’s use std:string::compare() to find the last occurrence of given string from position (Size of Main string – size of given string).
Case sensitive Implementation of endsWith using std::string::compare()
/*
* Case Sensitive Implementation of endsWith()
* It checks if the string 'mainStr' ends with given string 'toMatch'
*/
bool endsWith(const std::string &mainStr, const std::string &toMatch)
{
if(mainStr.size() >= toMatch.size() &&
mainStr.compare(mainStr.size() - toMatch.size(), toMatch.size(), toMatch) == 0)
return true;
else
return false;
}
Case sensitive Implementation of endsWith using std::all_of()
/*
* Case Sensitive Implementation of endsWith()
* It checks if the string 'mainStr' ends with given string 'toMatch'
*/
bool endsWith_secApproach(const std::string &mainStr, const std::string &toMatch)
{
auto it = toMatch.begin();
return mainStr.size() >= toMatch.size() &&
std::all_of(std::next(mainStr.begin(),mainStr.size() - toMatch.size()), mainStr.end(), [&it](const char & c){
return c == *(it++) ;
} );
}
Case Insensitive Implementation of endsWith using std::all_of()
/*
* Case Insensitive Implementation of endsWith()
* It checks if the string 'mainStr' ends with given string 'toMatch'
*/
bool endsWithCaseInsensitive(std::string mainStr, std::string toMatch)
{
auto it = toMatch.begin();
return mainStr.size() >= toMatch.size() &&
std::all_of(std::next(mainStr.begin(),mainStr.size() - toMatch.size()), mainStr.end(), [&it](const char & c){
return ::tolower(c) == ::tolower(*(it++)) ;
} );
}
Check complete example as follows,
#include <iostream>
#include <string>
#include <algorithm>
/*
* Case Sensitive Implementation of endsWith()
* It checks if the string 'mainStr' ends with given string 'toMatch'
*/
bool endsWith(const std::string &mainStr, const std::string &toMatch)
{
if(mainStr.size() >= toMatch.size() &&
mainStr.compare(mainStr.size() - toMatch.size(), toMatch.size(), toMatch) == 0)
return true;
else
return false;
}
/*
* Case Sensitive Implementation of endsWith()
* It checks if the string 'mainStr' ends with given string 'toMatch'
*/
bool endsWith_secApproach(const std::string &mainStr, const std::string &toMatch)
{
auto it = toMatch.begin();
return mainStr.size() >= toMatch.size() &&
std::all_of(std::next(mainStr.begin(),mainStr.size() - toMatch.size()), mainStr.end(), [&it](const char & c){
return c == *(it++) ;
} );
}
/*
* Case Insensitive Implementation of endsWith()
* It checks if the string 'mainStr' ends with given string 'toMatch'
*/
bool endsWithCaseInsensitive(std::string mainStr, std::string toMatch)
{
auto it = toMatch.begin();
return mainStr.size() >= toMatch.size() &&
std::all_of(std::next(mainStr.begin(),mainStr.size() - toMatch.size()), mainStr.end(), [&it](const char & c){
return ::tolower(c) == ::tolower(*(it++)) ;
} );
}
int main()
{
std::string mainStr = "This is the sample STRing";
std::string toMatch = "STRing";
// Test case-sensitive implementation of endsWith() function
bool result = endsWith(mainStr , toMatch);
std::cout<<result<<std::endl;
// Test case-sensitive implementation of endsWith_secApproach() function
result = endsWith_secApproach(mainStr , toMatch);
std::cout<<result<<std::endl;
// Test case-insensitive implementation of endsWith function
result = endsWithCaseInsensitive(toMatch, "String");
std::cout<<result<<std::endl;
}
Output:
1 1 1
std::string endsWith() using Boost Library
Boost’s algorithm library provides implementation of both case sensitive and insensitive implementation of endsWith() function for string i.e.
Case Sensitive Version :
boost::algorithm::ends_with(mainString, toMatchString) ;
Case Insensitive Version :
boost::algorithm::iends_with(mainString, toMatchString) ;
Header File required : <boost/algorithm/string.hpp>
Checkout complete example as follows,
#include <iostream>
#include <string>
#include <boost/algorithm/string.hpp>
int main()
{
std::string mainStr = "This is the sample STRing";
std::string toMatch = "STRing";
// Test case-sensitive implementation of endsWith function
bool result = boost::algorithm::ends_with(mainStr , toMatch);
std::cout<<result<<std::endl;
// Test case-insensitive implementation of endsWith function
result = boost::algorithm::iends_with(mainStr, "string");
std::cout<<result<<std::endl;
}
Output:
1 1