char_traits::to_char_type

转换 int_type 字符转换为相应的 char_type 字符并返回结果。

static char_type to_char_type(
   const int_type& _Ch
);

参数

• _Ch
  作为 char_type将表示的 int_type 字符。

返回值

与 int_type 字符相对应的 char_type 字符。

不能表示为此类添加一个未指定的结果 _Ch 的值。

备注

转换操作 to_int_type 和 to_char_type 彼此反的，因此，:

to_int_type ( to_char_type (x)) == x

对任何 int_typex 和

to_char_type ( to_int_type (x)) == x

对任何 char_typeX。

示例

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

int main( ) 
{
   using namespace std;

   char_traits<char>::char_type ch1 =  'a';
   char_traits<char>::char_type ch2 =  'b';
   char_traits<char>::char_type ch3 =  'a';

   // Converting from char_type to int_type
   char_traits<char>::int_type int1, int2 , int3;
   int1 =char_traits<char>:: to_int_type ( ch1 );
   int2 =char_traits<char>:: to_int_type ( ch2 );
   int3 =char_traits<char>:: to_int_type ( ch3 );

   cout << "The char_types and corresponding int_types are:"
        << "\n    ch1 = " << ch1 << " corresponding to int1 = " 
        << int1 << "."
        << "\n    ch2 = " << ch2 << " corresponding to int1 = " 
        << int2 << "."
        << "\n    ch3 = " << ch3 << " corresponding to int1 = " 
        << int3 << "." << endl << endl;
   
   // Converting from int_type back to char_type
   char_traits<char>::char_type rec_ch1;
   rec_ch1 = char_traits<char>:: to_char_type ( int1);
   char_traits<char>::char_type rec_ch2;
   rec_ch2 = char_traits<char>:: to_char_type ( int2);

   cout << "The recovered char_types and corresponding int_types are:"
        << "\n    recovered ch1 = " << rec_ch1 << " from int1 = " 
        << int1 << "."
        << "\n    recovered ch2 = " << rec_ch2 << " from int2 = " 
        << int2 << "." << endl << endl;
   
   // Testing that the conversions are inverse operations
   bool b1 = char_traits<char>::eq ( rec_ch1 , ch1 );
   if ( b1 )
      cout << "The recovered char_type of ch1"
           << " is equal to the original ch1." << endl;
   else
      cout << "The recovered char_type of ch1"
           << " is not equal to the original ch1." << endl;

   // An equivalent and alternatively test procedure
   if ( rec_ch2 == ch2 )
      cout << "The recovered char_type of ch2"
           << " is equal to the original ch2." << endl;
   else
      cout << "The recovered char_type of ch2"
           << " is not equal to the original ch2." << endl;
}

要求

标头: <string>

命名空间: std

请参见

参考

char_traits Struct