In this article, we will be discussing starts_with() and ends_with() with examples in C++20.
starts_with()
This function efficiently checks if a string begins with the given prefix or not. This function written in both std::basic_string and in std::basic_string_view.
Syntax:
template <typename PrefixType> bool starts_with(PrefixType prefix)
In the above syntax the prefix can be:
- string
- string view
- single character or C-style string with null-terminated character
starts_with() with different types of Prefix:
bool starts_with(std::basic_string_view<Char T, Traits> x) const noexcept;
bool starts_with(CharT x) const noexcept;
bool starts_with(const CharT *x) const;
All the three overloaded forms of the function effectively return std::basic_string_view<Char T, Traits>(data(), size()).starts_with(x);
Parameters: It requires a single character sequence or a single character to compare to the start of the string.
Return Value: It returns the boolean true or false indication the following:
- True: If string starts with the prefix.
- False: If string does not start with the prefix.
Program 1:
Below program to demonstrates the concept of starts_with() in C++:
C++
// C++ program to illustrate the use // of starts_with() #include <iostream> #include <string> #include <string_view> using namespace std; // Function template to check if the // given string starts with the given // prefix or not template <typename PrefixType> void if_prefix(const std::string& str, PrefixType prefix) { cout << "'" << str << "' starts with '" << prefix << "': " << str.starts_with(prefix) << endl; } // Driver Code int main() { string str = { "neveropen" }; if_prefix(str, string("geek")); // prefix is string if_prefix(str, string_view("geek")); // prefix is string view if_prefix(str, 'g'); // prefix is single character if_prefix(str, "geek\0"); // prefix is C-style string if_prefix(str, string("for")); if_prefix(str, string("Geek")); if_prefix(str, 'x'); return 0; } |
Output:
This function efficiently checks if a string ends with the given suffix or not. This function written in both std::basic_string and in std::basic_string_view.
Syntax:
template <typename SuffixType> bool starts_with(SuffixType suffix)
In the above syntax the suffix can be:
- string
- string view
- single character or C-style string with null-terminated character.
ends with() different types of Suffix:
constexpr bool ends_with(std::basic_string_view<Char T, Traits> sv) const noexcept;|
constexpr boll ends_with(CharT c) const noexcept;
constexpr bool ends_with(const CharT* s) const;
All the three overloaded forms of the function effectively return std::basic_string_view<Char T, Traits>(data(), size()).ends_with(x);
Parameters: It requires a single character sequence or a single character to compare to the end of the string.
Return Value: It returns the boolean true or false indicating the following:
- True: If string ends with the suffix.
- False: If string does not end with the suffix.
Program 2:
Below program to demonstrates the concept of ends_with() in C++:
C++
// C++ program to illustrate the use // of ends_with() #include <iostream> #include <string> #include <string_view> using namespace std; // Function template to check if the // given string ends_with given string template <typename SuffixType> void if_suffix(const std::string& str, SuffixType suffix) { cout << "'" << str << "' ends with '" << suffix << "': " << str.ends_with(suffix) << std::endl; } // Driver Code int main() { string str = { "neveropen" }; if_suffix(str, string("neveropen")); // suffix is string if_suffix(str, string_view("neveropen")); // suffix is string view if_suffix(str, 's'); // suffix is single character if_suffix(str, "neveropen\0"); // suffix is C-style string if_suffix(str, string("for")); if_suffix(str, string("Geeks")); if_suffix(str, 'x'); if_suffix(str, '\0'); } |
Output:
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