std::basic_string::find_first_of

 

C++

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Regular expressions library (C++11)

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Technical Specifications

 

Strings library

Null-terminated strings

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Classes

basic_string

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)

Operations basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::swap Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Constants basic_string::npos

Non-member functions operator+ operator==operator!=operator<operator>operator<=operator>= swap(std::basic_string) operator<<operator>> getline stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Helper classes hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string> (C++11)(C++11)(C++11)(C++11)

 

size_type find_first_of( const basic_string& str, size_type pos = 0 ) const;	(1)
size_type find_first_of( const CharT* s, size_type pos, size_type count ) const;	(2)
size_type find_first_of( const CharT* s, size_type pos = 0 ) const;	(3)
size_type find_first_of( CharT ch, size_type pos = 0 ) const;	(4)

Finds the first character equal to one of the characters in the given character sequence. The search considers only the interval [pos, size()). If the character is not present in the interval, npos will be returned.

1) Finds the first character equal to one of the characters in str.

2) Finds the first character equal to one of the characters in the first count characters of the character string pointed to by s. s can include null characters.

3) Finds the first character equal to one of the characters in character string pointed to by s. The length of the string is determined by the first null character.

4) Finds the first character equal to ch.

Parameters

str	-	string identifying characters to search for
pos	-	position at which to begin searching
count	-	length of character string identifying characters to search for
s	-	pointer to a character string identifying characters to search for
ch	-	character to search for

Return value

Position of the found character or npos if no such character is found.

Exceptions

1-4) (none)	(until C++11)
1,4) noexcept specification:   noexcept    2,3) (none)	(since C++11) (until C++14)
1) noexcept specification:   noexcept    2-4) (none)	(since C++14)

Notes

traits::eq() is used to perform the comparison.

Example

Run this code

#include <iostream>
#include <string>
 
int main()
{
    // the test string
    std::string str = std::string("Hello World!");
 
    // strings and chars to search for
    std::string search_str = std::string("o");
    const char* search_cstr = "Good Bye!";
 
    std::cout << str.find_first_of(search_str) << '\n';
    std::cout << str.find_first_of(search_str, 5) << '\n';
    std::cout << str.find_first_of(search_cstr) << '\n';
    std::cout << str.find_first_of(search_cstr, 0, 4) << '\n';
    // 'x' is not in "Hello World', thus it will return std::string::npos
    std::cout << str.find_first_of('x') << '\n';
}

Possible output:

4
7
1
4
18446744073709551615

See also

find	find characters in the string (public member function)
rfind	find the last occurrence of a substring (public member function)
find_first_not_of	find first absence of characters (public member function)
find_last_of	find last occurrence of characters (public member function)
find_last_not_of	find last absence of characters (public member function)