basic_string::begin

返回解决的迭代器在字符串的第一个元素。

const_iterator begin( ) const;
iterator begin( );

返回值

解决序列的第一个元素或在一个空序列之外的末尾的一个随机访问迭代器。

备注

如果 begin 的返回值赋给 const_iterator，不能修改字符串对象。 如果 begin 的返回值赋给 iterator，可以修改字符串对象。

示例

// 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.

要求

标头: <string>

命名空间: std

请参见

参考

basic_string Class