basic_string::begin

傳回所定址的 Iterator 位於字串的第一個項目。

const_iterator begin( ) const;
iterator begin( );

傳回值

若要解決這個序列中的第一個項目或在空的序列結尾的隨機存取 Iterator。

註解

如果 begin 的傳回值指派給 const_iterator，無法修改字串物件。 如果 begin 的傳回值指派給 iterator，可以修改字串物件。

範例

// basic_string_begin.cpp
// compile with: /EHsc
#include <string>
#include <iostream>

int main( ) {
   using namespace std;
   string str1 ( "No way out." ), str2;
   basic_string <char>::iterator strp_Iter, str1_Iter, str2_Iter;
   basic_string <char>::const_iterator str1_cIter;

   str1_Iter = str1.begin ( );
   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 << "The first character of the modified 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
   if (  str2.begin ( ) == str2.end ( ) )
      cout << "The string str2 is empty." << endl;
   else
      cout << "The string str2 is not empty." << endl;
}

Output

The first character of the string str1 is: N
The full original string str1 is: No way out.
The first character of the modified str1 is now: G
The full modified string str1 is now: Go way out.
The string str2 is empty.

需求

標題: <string>

命名空間: std

請參閱

參考

basic_string Class