basic_string::capacity

Returns the largest number of elements that could be stored in a string without increasing the memory allocation of the string.

size_type capacity( ) const;

Return Value

The size of storage currently allocated in memory to hold the string.

Remarks

The member function returns the storage currently allocated to hold the controlled sequence, a value at least as large as size.

Example

// 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;
}

Sample Output

The following output is for 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.

Requirements

Header: <string>

Namespace: std

See Also

Reference

basic_string Class