public static member function
<string>
static bool eq (const char_type& c, const char_type& d);
static constexpr bool eq (char_type c, char_type d) noexcept;
Compare characters for equality
Returns whether characters c and d are considered equal.
In the standard specializations of
char_traits, this function behaves as the built-in
operator==, but custom
character traits classes may provide an alternative behavior.
In the standard specializations of
char_traits, this function behaves as the built-in
operator== for type
unsigned char, but custom
character traits classes may provide an alternative behavior.
Parameters
- c, d
- Character values.
Member type char_type is the character type (i.e., the class template parameter in char_traits).
Return Value
true if c is considered equal to d.
Example
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| // char_traits::eq #include <iostream> // std::cout #include <string> // std::basic_string, std::char_traits #include <cctype> // std::tolower #include <cstddef> // std::size_t // traits with case-insensitive eq: struct custom_traits: std::char_traits<char> { static bool eq (char c, char d) { return std::tolower(c)==std::tolower(d); } // some (non-conforming) implementations of basic_string::find call this instead of eq: static const char* find (const char* s, std::size_t n, char c) { while( n-- && (!eq(*s,c)) ) ++s; return s; } }; int main () { std::basic_string<char,custom_traits> str ("Test"); std::cout << "T found at position " << str.find('t') << '\n'; return 0; }
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Output:
Exception safety
No-throw guarantee: this member function never throws exceptions in any of the standard specializations.