basic_string::find_first_of
Searches through a string for the first character that matches any element of a specified string.
size_type find_first_of(
value_type _Ch,
size_type _Off = 0
) const;
size_type find_first_of(
const value_type* _Ptr,
size_type _Off = 0
) const;
size_type find_first_of(
const value_type* _Ptr,
size_type _Off,
size_type _Count
) const;
size_type find_first_of(
const basic_string<CharType, Traits, Allocator>& _Str,
size_type _Off = 0
) const;
Parameters
_Ch
The character value for which the member function is to search._Off
Index of the position at which the search is to begin._Ptr
The C-string for which the member function is to search._Count
The number of characters, counting forward from the first character, in the C-string for which the member function is to search._Str
The string for which the member function is to search.
Return Value
The index of the first character of the substring searched for when successful; otherwise npos.
Example
// basic_string_find_first_of.cpp
// compile with: /EHsc
#include <string>
#include <iostream>
int main( )
{
using namespace std;
// The first member function
// searches for a single character in a string
string str1 ( "abcd-1234-abcd-1234" );
cout << "The original string str1 is: " << str1 << endl;
basic_string <char>::size_type indexCh1a, indexCh1b;
static const basic_string <char>::size_type npos = -1;
indexCh1a = str1.find_first_of ( "d" , 5 );
if ( indexCh1a != npos )
cout << "The index of the 1st 'd' found after the 5th"
<< " position in str1 is: " << indexCh1a << endl;
else
cout << "The character 'd' was not found in str1 ." << endl;
indexCh1b = str1.find_first_of ( "x" );
if ( indexCh1b != npos )
cout << "The index of the 'x' found in str1 is: "
<< indexCh1b << endl << endl;
else
cout << "The character 'x' was not found in str1."
<< endl << endl;
// The second member function searches a string
// for a substring as specified by a C-string
string str2 ( "ABCD-1234-ABCD-1234" );
cout << "The original string str2 is: " << str2 << endl;
basic_string <char>::size_type indexCh2a, indexCh2b;
const char *cstr2 = "B1";
indexCh2a = str2.find_first_of ( cstr2 , 6 );
if ( indexCh2a != npos )
cout << "The index of the 1st occurrence of an "
<< "element of 'B1' in str2 after\n the 6th "
<< "position is: " << indexCh2a << endl;
else
cout << "Elements of the substring 'B1' were not "
<< "found in str2 after the 10th position."
<< endl;
const char *cstr2b = "D2";
indexCh2b = str2.find_first_of ( cstr2b );
if ( indexCh2b != npos )
cout << "The index of the 1st element of 'D2' "
<< "after\n the 0th position in str2 is: "
<< indexCh2b << endl << endl;
else
cout << "The substring 'D2' was not found in str2 ."
<< endl << endl << endl;
// The third member function searches a string
// for a substring as specified by a C-string
string str3 ( "123-abc-123-abc-456-EFG-456-EFG" );
cout << "The original string str3 is: " << str3 << endl;
basic_string <char>::size_type indexCh3a, indexCh3b;
const char *cstr3a = "5G";
indexCh3a = str3.find_first_of ( cstr3a );
if ( indexCh3a != npos )
cout << "The index of the 1st occurrence of an "
<< "element of '5G' in str3 after\n the 0th "
<< "position is: " << indexCh3a << endl;
else
cout << "Elements of the substring '5G' were not "
<< "found in str3\n after the 0th position."
<< endl;
const char *cstr3b = "5GF";
indexCh3b = str3.find_first_of ( cstr3b , indexCh3a + 1 , 2 );
if (indexCh3b != npos )
cout << "The index of the second occurrence of an "
<< "element of '5G' in str3\n after the 0th "
<< "position is: " << indexCh3b << endl << endl;
else
cout << "Elements of the substring '5G' were not "
<< "found in str3\n after the first occurrrence."
<< endl << endl;
// The fourth member function searches a string
// for a substring as specified by a string
string str4 ( "12-ab-12-ab" );
cout << "The original string str4 is: " << str4 << endl;
basic_string <char>::size_type indexCh4a, indexCh4b;
string str4a ( "ba3" );
indexCh4a = str4.find_first_of ( str4a , 5 );
if ( indexCh4a != npos )
cout << "The index of the 1st occurrence of an "
<< "element of 'ba3' in str4 after\n the 5th "
<< "position is: " << indexCh4a << endl;
else
cout << "Elements of the substring 'ba3' were not "
<< "found in str4\n after the 0th position."
<< endl;
string str4b ( "a2" );
indexCh4b = str4.find_first_of ( str4b );
if ( indexCh4b != npos )
cout << "The index of the 1st occurrence of an "
<< "element of 'a2' in str4 after\n the 0th "
<< "position is: " << indexCh4b << endl;
else
cout << "Elements of the substring 'a2' were not "
<< "found in str4\n after the 0th position."
<< endl;
}
The original string str1 is: abcd-1234-abcd-1234 The index of the 1st 'd' found after the 5th position in str1 is: 13 The character 'x' was not found in str1. The original string str2 is: ABCD-1234-ABCD-1234 The index of the 1st occurrence of an element of 'B1' in str2 after the 6th position is: 11 The index of the 1st element of 'D2' after the 0th position in str2 is: 3 The original string str3 is: 123-abc-123-abc-456-EFG-456-EFG The index of the 1st occurrence of an element of '5G' in str3 after the 0th position is: 17 The index of the second occurrence of an element of '5G' in str3 after the 0th position is: 22 The original string str4 is: 12-ab-12-ab The index of the 1st occurrence of an element of 'ba3' in str4 after the 5th position is: 9 The index of the 1st occurrence of an element of 'a2' in str4 after the 0th position is: 1
Requirements
Header: <string>
Namespace: std
See Also
Reference
basic_string::find_first_of (STL Samples)