C++

Reference

<string>

string

public member function
<string>

std::string::find_first_of

string (1)
size_t find_first_of (const string& str, size_t pos = 0) const;
c-string (2)
size_t find_first_of (const char* s, size_t pos = 0) const;
buffer (3)
size_t find_first_of (const char* s, size_t pos, size_t n) const;
character (4)
size_t find_first_of (char c, size_t pos = 0) const;
string (1)
size_t find_first_of (const string& str, size_t pos = 0) const noexcept;
c-string (2)
size_t find_first_of (const char* s, size_t pos = 0) const;
buffer (3)
size_t find_first_of (const char* s, size_t pos, size_t n) const;
character (4)
size_t find_first_of (char c, size_t pos = 0) const noexcept;
Find character in string
Searches the string for the first character that matches any of the characters specified in its arguments.

When pos is specified, the search only includes characters at or after position pos, ignoring any possible occurrences before pos.

Notice that it is enough for one single character of the sequence to match (not all of them). See string::find for a function that matches entire sequences.

Parameters

str
Another string with the characters to search for.
pos
Position of the first character in the string to be considered in the search.
If this is greater than the string length, the function never finds matches.
Note: The first character is denoted by a value of 0 (not 1): A value of 0 means that the entire string is searched.
s
Pointer to an array of characters.
If argument n is specified (3), the first n characters in the array are searched for.
Otherwise (2), a null-terminated sequence is expected: the length of the sequence with the characters to match is determined by the first occurrence of a null character.
n
Number of character values to search for.
c
Individual character to be searched for.

size_t is an unsigned integral type (the same as member type string::size_type).

Return Value

The position of the first character that matches.
If no matches are found, the function returns string::npos.

size_t is an unsigned integral type (the same as member type string::size_type).

Example

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// string::find_first_of
#include <iostream>       // std::cout
#include <string>         // std::string
#include <cstddef>        // std::size_t

int main ()
{
  std::string str ("Please, replace the vowels in this sentence by asterisks.");
  std::size_t found = str.find_first_of("aeiou");
  while (found!=std::string::npos)
  {
    str[found]='*';
    found=str.find_first_of("aeiou",found+1);
  }

  std::cout << str << '\n';

  return 0;
}
 

Pl**s*, r*pl*c* th* v*w*ls *n th*s s*nt*nc* by *st*r*sks.


Complexity

Unspecified, but generally up to linear in length()-pos times the number of characters to match (worst case).

Iterator validity

No changes.

Data races

The object is accessed.

Exception safety

If s does not point to an array long enough, it causes undefined behavior.
Otherwise, the function never throws exceptions (no-throw guarantee).

See also

string::find
Find content in string (public member function)
string::find_last_of
Find character in string from the end (public member function)
string::find_first_not_of
Find absence of character in string (public member function)
string::replace
Replace portion of string (public member function)
string::substr
Generate substring (public member function)