C++ STL  basic_string::begin() iterator program example

 

Compiler: Visual C++ Express Edition 2005

Compiled on Platform: Windows XP Pro SP2

Header file: Standard

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++ basic_string::begin() iterator which return an iterator addressing the first element in the string in C++ programming

To show: How to use the basic_string begin() iterator which return an iterator addressing the first element in the string in C++ programming

 

// C++ STL basic_string, iterator, begin()

#include <string>

#include <iostream>

using namespace std;

 

int main(void)

{

// container and iterators

string str1 ("This is a test string."), str2;

basic_string <char>::iterator strp_Iter, str1_Iter, str2_Iter;

basic_string <char>::const_iterator str1_cIter;

str1_Iter = str1.begin();

 

// printing the data

cout<<"\nOperation: str1_Iter = str1.begin()"<<endl;

cout<<"The first character of the string str1 is: "<<*str1_Iter<<endl;

cout<<"The full original string str1 is: "<<str1<<endl;

 

// the dereferenced iterator can be used to modify a character

*str1_Iter = 'G';

cout<<"\nOperation: *str1_Iter = \'G\'"<<endl;

cout<<"The first character of the modified string str1 is now: "<<*str1_Iter<<endl;

cout<<"The full modified string str1 is now: "<<str1<<endl;

 

// the following line would be an error because iterator is const

//

// *str1_cIter = 'g';

//

// for an empty string, begin() is equivalent to end()

cout<<"\nOperation: *str2.begin() == str2.end()?"<<endl;

if (str2.begin() == str2.end())

cout<<"The string str2 is empty."<<endl;

else

cout<<"The string str2 is not empty."<<endl;

return 0;

}

 

Output examples:

 

Operation: str1_Iter = str1.begin()

The first character of the string str1 is: T

The full original string str1 is: This is a test string.

Operation: *str1_Iter = 'G'

The first character of the modified string str1 is now: G

The full modified string str1 is now: Ghis is a test string.

Operation: *str2.begin() == str2.end()?

The string str2 is empty.

Press any key to continue . . .

 

 

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