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
#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 characters in the string (public member function) | |
| find the last occurrence of a substring (public member function) | |
| find first absence of characters (public member function) | |
| find last occurrence of characters (public member function) | |
| find last absence of characters (public member function) |
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