cpp vector code example

Example 1: c++ vector

#include <vector>

int main() {
  std::vector<int> v;
  v.push_back(10); // v = [10];
  v.push_back(20); // v = [10, 20];
  
  v.pop_back(); // v = [10];
  v.push_back(30); // v = [10, 30];
  
  auto it = v.begin();
  int x = *it; // x = 10;
  ++it;
  int y = *it; // y = 30
  ++it;
  bool is_end = it == v.end(); // is_end = true
  
  return 0;
}

Example 2: std vector include c++

#include <vector>
std::vector<std::string> x;

Example 3: vector c++

Vectors are sequence container that can change size. Container is a objects 
that hold data of same type. Sequence containers store elements strictly in 
linear sequence.

Vector stores elements in contiguous memory locations and enables direct access
to any element using subscript operator []. Unlike array, vector can shrink or
expand as needed at run time. The storage of the vector is handled automatically.

To support shrink and expand functionality at runtime, vector container may 
allocate some extra storage to accommodate for possible growth thus container
have actual capacity greater than the size. Therefore, compared to array, vector
consumes more memory in exchange for the ability to manage storage and grow 
dynamically in an efficient way.

Zero sized vectors are also valid. In that case vector.begin() and vector.end()
points to same location. But behavior of calling front() or back() is undefined.

Example 4: vector in c

#include <iostream> 
#include <vector> 
  
using namespace std; 
  
int main() 
{ 
    vector<int> g1; 
  
    for (int i = 1; i <= 5; i++) 
        g1.push_back(i); 
  
    cout << "Output of begin and end: "; 
    for (auto i = g1.begin(); i != g1.end(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of cbegin and cend: "; 
    for (auto i = g1.cbegin(); i != g1.cend(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of rbegin and rend: "; 
    for (auto ir = g1.rbegin(); ir != g1.rend(); ++ir) 
        cout << *ir << " "; 
  
    cout << "\nOutput of crbegin and crend : "; 
    for (auto ir = g1.crbegin(); ir != g1.crend(); ++ir) 
        cout << *ir << " "; 
  
    return 0; 
}

Example 5: vector in c++

vector<int> g1; 
  
    for (int i = 1; i <= 5; i++) 
        g1.push_back(i); 
  
    cout << "Output of begin and end: "; 
    for (auto i = g1.begin(); i != g1.end(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of cbegin and cend: "; 
    for (auto i = g1.cbegin(); i != g1.cend(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of rbegin and rend: "; 
    for (auto ir = g1.rbegin(); ir != g1.rend(); ++ir) 
        cout << *ir << " ";

Example 6: how to use vectors c++

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

int main() {
  //vector element size
  const int size = 4; 
  //vector with int data type
  //all elements are equal to 4
  vector<int> myVect (size, 4);

  for (int i=0; i<size; i++) {
    cout << "Vector index(" << i <<") is: "<< myVect[i] << endl; 
  }
  return 0;
}