Check out example codes for "c++ vector". It will help you in understanding the concepts better.

Code Example 1

#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; 
}

Code Example 2

// C++ program to illustrate the 
// Modifiers in vector 
#include <bits/stdc++.h> 
#include <vector> 
using namespace std; 
  
int main() 
{ 
    // Assign vector 
    vector<int> v; 
  
    // fill the array with 10 five times 
    v.assign(5, 10); 
  
    cout << "The vector elements are: "; 
    for (int i = 0; i < v.size(); i++) 
        cout << v[i] << " "; 
  
    // inserts 15 to the last position 
    v.push_back(15); 
    int n = v.size(); 
    cout << "\nThe last element is: " << v[n - 1]; 
  
    // removes last element 
    v.pop_back(); 
  
    // prints the vector 
    cout << "\nThe vector elements are: "; 
    for (int i = 0; i < v.size(); i++) 
        cout << v[i] << " "; 
  
    // inserts 5 at the beginning 
    v.insert(v.begin(), 5); 
  
    cout << "\nThe first element is: " << v[0]; 
  
    // removes the first element 
    v.erase(v.begin()); 
  
    cout << "\nThe first element is: " << v[0]; 
  
    // inserts at the beginning 
    v.emplace(v.begin(), 5); 
    cout << "\nThe first element is: " << v[0]; 
  
    // Inserts 20 at the end 
    v.emplace_back(20); 
    n = v.size(); 
    cout << "\nThe last element is: " << v[n - 1]; 
  
    // erases the vector 
    v.clear(); 
    cout << "\nVector size after erase(): " << v.size(); 
  
    // two vector to perform swap 
    vector<int> v1, v2; 
    v1.push_back(1); 
    v1.push_back(2); 
    v2.push_back(3); 
    v2.push_back(4); 
  
    cout << "\n\nVector 1: "; 
    for (int i = 0; i < v1.size(); i++) 
        cout << v1[i] << " "; 
  
    cout << "\nVector 2: "; 
    for (int i = 0; i < v2.size(); i++) 
        cout << v2[i] << " "; 
  
    // Swaps v1 and v2 
    v1.swap(v2); 
  
    cout << "\nAfter Swap \nVector 1: "; 
    for (int i = 0; i < v1.size(); i++) 
        cout << v1[i] << " "; 
  
    cout << "\nVector 2: "; 
    for (int i = 0; i < v2.size(); i++) 
        cout << v2[i] << " "; 
}

Code Example 3

// CPP program to initialize a vector from 
// another vector. 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    vector<int> vect1{ 10, 20, 30 }; 
  
    vector<int> vect2(vect1.begin(), vect1.end()); 
  
    for (int x : vect2) 
        cout << x << " "; 
  
    return 0; 
}

Code Example 4

// vector::operator[]
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector (10);   // 10 zero-initialized elements

  std::vector<int>::size_type sz = myvector.size();

  // assign some values:
  for (unsigned i=0; i<sz; i++) myvector[i]=i;

  // reverse vector using operator[]:
  for (unsigned i=0; i<sz/2; i++)
  {
    int temp;
    temp = myvector[sz-1-i];
    myvector[sz-1-i]=myvector[i];
    myvector[i]=temp;
  }

  std::cout << "myvector contains:";
  for (unsigned i=0; i<sz; i++)
    std::cout << ' ' << myvector[i];
  std::cout << '\n';

  return 0;
}

Code Example 5

#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;
}

Code Example 6

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

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