basic_string::capacity

返回字符串中可以存储，而不递增字符串的内存分配元素的方法。

size_type capacity( ) const;

返回值

在当前内存分配存储的大小一个包含字符串。

备注

成员函数返回当前分配的存储包含该控件序列，值至少与大到 范围。

示例

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

int main( ) 
{
   using namespace std;
   string  str1 ("Hello world");
   cout << "The original string str1 is: " << str1 << endl;

   // The size and length member functions differ in name only
   basic_string <char>::size_type sizeStr1, lenStr1;
   sizeStr1 = str1.size ( );
   lenStr1 = str1.length ( );

   basic_string <char>::size_type capStr1, max_sizeStr1;
   capStr1 = str1.capacity ( );
   max_sizeStr1 = str1.max_size ( );

   // Compare size, length, capacity & max_size of a string
   cout << "The current size of original string str1 is: " 
        << sizeStr1 << "." << endl;
   cout << "The current length of original string str1 is: " 
        << lenStr1 << "." << endl;
   cout << "The capacity of original string str1 is: "
        << capStr1 << "." << endl;
   cout << "The max_size of original string str1 is: " 
        << max_sizeStr1 << "." << endl << endl;

   str1.erase ( 6, 5 );
   cout << "The modified string str1 is: " << str1 << endl;

   sizeStr1 = str1.size (  );
   lenStr1 = str1.length (  );
   capStr1 = str1.capacity (  );
   max_sizeStr1 = str1.max_size (  );

   // Compare size, length, capacity & max_size of a string
   // after erasing part of the original string
   cout << "The current size of modified string str1 is: " 
        << sizeStr1 << "." << endl;
   cout << "The current length of modified string str1 is: " 
        << lenStr1 << "." << endl;
   cout << "The capacity of modified string str1 is: "
        << capStr1 << "." << endl;
   cout << "The max_size of modified string str1 is: " 
        << max_sizeStr1 << "." << endl;
}

示例输出

下面的输出是针对x86。

The original string str1 is: Hello world
The current size of original string str1 is: 11.
The current length of original string str1 is: 11.
The capacity of original string str1 is: 15.
The max_size of original string str1 is: 4294967294.

The modified string str1 is: Hello 
The current size of modified string str1 is: 6.
The current length of modified string str1 is: 6.
The capacity of modified string str1 is: 15.
The max_size of modified string str1 is: 4294967294.

要求

标头: <string>

命名空间: std

请参见

参考

basic_string Class