The C++ find_first_of() member function program example part I

 

Compiler: Visual C++ Express Edition 2005

Compiled on Platform: Windows XP Pro SP2

Header file: Standard

Additional library: none/default

Additional project setting: Set project to be compiled as C++

Project -> your_project_name Properties -> Configuration Properties -> C/C++ -> Advanced -> Compiled As: Compiled as C++ Code (/TP)

Other info: none

To do: Using the C++ find_first_of() member function to search through a string for the first character that matches any element of a specified string part I

To show: How to use the C++ find_first_of() member function to search through a string for the first character that matches any element of a specified string part I

 

// the C++ find_first_of() program example part I

#include <string>

#include <iostream>

using namespace std;

 

int main(void)

{

// searching for a single character in a string

string str1("find_first_of()");

cout<<"str1 string is: "<<str1<<endl;

basic_string <char>::size_type index1, index2;

static const basic_string <char>::size_type npos = -1;

index1 = str1.find_first_of('r', 3);

 

cout<<"Operation: str1.find_first_of('r', 3)"<<endl;

if(index1 != npos)

cout<<"The index of the 1st 'r' found after the 3rd "

<<"position in str1 is: "<<unsigned int(index1)<<endl;

else

cout<<"The character 'r' was not found in str1"<<endl;

index2 = str1.find_first_of('z');

 

cout<<"\nOperation: str1.find_first_of('z')"<<endl;

if(index2 != npos)

cout<<"The index of the 'z' found in str1 is: "<<unsigned int(index2)<<endl;

else

cout<<"The character 'z' was not found in str1."<<endl;

 

// searching a string for a substring as specified by a C-string

string str2("Testing 123...Testing 123");

cout<<"\nstr2 string is: "<<str2<<endl;

basic_string <char>::size_type index3, index4;

const char *cstr = "s1";

index3 = str2.find_first_of(cstr, 3);

 

cout<<"Operation: str2.find_first_of(cstr, 3)"<<endl;

if(index3 != npos)

cout<<"The index of the 1st occurrence of an "

<<"element of 's1' in str2 after the 3rd "

<<"position is: "<<unsigned int(index3)<<endl;

else

cout<<"Elements of the substring 's1' were not "

<<"found in str2 after the 3rd position."<<endl;

const char *cstr1 = "g3";

index4 = str2.find_first_of(cstr1);

 

cout<<"\nOperation: str2.find_first_of(cstr1)"<<endl;

if(index4 != npos)

cout <<"The index of the 1st element of 'g3' "

<<"after the 0th position in str2 is: "<<unsigned int(index4)<<endl;

else

cout<<"The substring 'g3' was not found in str2."<<endl;

 

return 0;

}

 

Output example:

 

str1 string is: find_first_of()

Operation: str1.find_first_of('r', 3)

The index of the 1st 'r' found after the 3rd position in str1 is: 7

 

Operation: str1.find_first_of('z')

The character 'z' was not found in str1.

 

str2 string is: Testing 123...Testing 123

Operation: str2.find_first_of(cstr, 3)

The index of the 1st occurrence of an element of 's1' in str2 after the 3rd position is: 8

 

Operation: str2.find_first_of(cstr1)

The index of the 1st element of 'g3' after the 0th position in str2 is: 6

Press any key to continue . . .

 

 

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