Cpp > Programs

cpp vector , push_back. pop_back example

#include <iostream>
#include <vector>
using namespace std;

typedef vector<int> intVector;
typedef vector<int>::iterator ivItor;

template<class T, class A>
void ShowVector(const vector<T, A>& v);

int main()
{
intVector vInt(5); // define a vector of integers with 3 elements
cout << "vInt(5)" << "\n";

// assign a value to each element in vInt using subscripts
for (vector<int>::size_type i = 0; i < vInt.size(); ++i)
vInt[i] = 5 * i;

ShowVector(vInt);

// insert an element
cout << "vInt after insert(vInt.begin() + 1, 50)\n";
ivItor itor = vInt.insert(vInt.begin() + 1, 50);
ShowVector(vInt);
cout << "Current element is " << *itor << "\n\n";

// insert 5 element
cout << "vInt after insert(vInt.end(), 5, 30)\n";
vInt.insert(vInt.end(), 5, 30);
ShowVector(vInt);

// erase one element from vInt
cout << "vInt after erase one element\n";
vInt.erase(vInt.begin() + 3);
ShowVector(vInt);

// erase three element from vInt
cout << "vInt after erase three element\n";
vInt.erase(vInt.begin() + 3, vInt.begin() + 6);
ShowVector(vInt);

// insert several elements from another vector
intVector vInt2(2);
cout << "vInt2" << "\n";
ShowVector(vInt2);

cout << "vInt2 after insert from vInt\n";
vInt2.insert(vInt2.begin() + 1, vInt.begin() + 1, vInt.begin() + 3);
ShowVector(vInt2);

// add an element at the end of vInt2
cout << "vInt2 after push_back()\n";
vInt2.push_back(100);
ShowVector(vInt2);

// remove an element from the end of vInt2
cout << "vInt2 after pop_back()\n";
vInt2.pop_back();
ShowVector(vInt2);

// clear vInt2
cout << "vInt2 cleared\n";
vInt2.clear();
ShowVector(vInt2);

return 0;
}

//
// Display vector properties
//
template<class T, class A>
void ShowVector(const vector<T, A>& v)
{
cout << "size() = " << v.size() << "\tcapacity() = " << v.capacity() << "\n";

// traverse through the vector using subscripts
cout << "elements:\t";
for (vector<T, A>::size_type i = 0; i < v.size(); ++i)
cout << v[i] << ", ";

cout << "\n\n";
}