STL Sample for the vector::(capacity size push_back) Functions

• The Standard C++ Library included with: - Microsoft Visual C++, 32-bit Edition, version 4.2

SUMMARY

The sample code below illustrates how to use the vector::size, vector::capacity, and vector::push_back functions.

MORE INFORMATION

Required Header

   <vector>

Prototypes

   size_type vector::capacity() const
   size_type vector::size() const
   void vector::push_back(const _TYPE& _X)

Description

• The sample declares an empty vector of integers.
• It outputs the size and capacity of the vector.
• It adds a single element to the vector, then outputs the size and capacity again.

Sample Code

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// Capacity.cpp  - Illustrates vector::capacity and vector::size
//
// Functions:
//
//    vector::capacity  - Return # of elements for which memory has
//                        been allocated.
//
//    vector::size      - Return # of elements in the vector
//
//    vector::push_back - Append (insert) an element to the end of a
//                        vector, allocating memory for it if necessary.
//
// Written by Tom Campbell
// of Microsoft Corporation
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////

// The debugger can't handle symbols more than 255 characters long.
// STL often creates symbols longer than that.
// This disables the warning issued when symbols are longer than 255 chars.

#include <iostream>
#include <vector>

void main()

    // Dynamically allocated vector begins with 0 elements.
    INTVECTOR theVector;

    // Show size (current # of elements) and capacity (# of elements
    // there's room for) of the empty vector.
    cout << endl << "Vector with no elements:" << endl;
    cout << "theVector's size is: " << theVector.size() << endl;
    cout << "theVector's capacity is: " << theVector.capacity() << endl;

    // Add one element to the end of the vector, an int with the value 42.
    // Allocate memory if necessary.
    theVector.push_back(42) ;

    // Show size & capacity after adding an element to the vector.
    cout << endl << "After adding 1 element:" << endl;
    cout << "theVector's size is: " << theVector.size() << endl;
    cout << "theVector's capacity is: " << theVector.capacity() << endl;

REFERENCES

Visual C++ Books On Line: Visual C++ Books:C/C++: Standard C++ Library Reference.