In this C++ tutorial, you will learn how to get the size or length of a vector using vector::size() function, with examples.
C++ Vector Size
To get the size of a C++ Vector, you can use size() function on the vector.
size() function returns the number of elements in the vector.
Examples
1. Find Vector Length using size()
In the following C++ program, we define a vector of integers, add some elements to it, and then find its length using size() function.
C++ Program
#include <iostream> #include <vector> using namespace std; int main() { vector<int> nums; nums.push_back(24); nums.push_back(81); nums.push_back(57); cout << nums.size(); }
Output
3
2. Length of Empty Vector
In the following C++ program, we define a vector of integers, with no elements in it, and then find its length using size() function. size() should return a value of zero.
C++ Program
#include <iostream> #include <vector> using namespace std; int main() { vector<int> nums; cout << nums.size(); }
Output
0
3. Length of Vector using Foreach
You can also use C++ Foreach statement to get the length of size of a vector.
In the following program, we shall define a vector and initialize with elements. Then take a len variable with zero initial value that acts as a counter to count the number of elements in the vector. Use Foreach statement to iterate over the elements of vector and increment the counter during each iteration.
C++ Program
#include <iostream> #include <vector> using namespace std; int main() { vector<int> nums; nums.push_back(24); nums.push_back(81); nums.push_back(57); int len = 0; for (int element: nums) len++; cout << len; }
Output
3
Conclusion
In this C++ Tutorial, we learned to find the size of vector, which is the number of elements in a vector using builtin functions or statements like foreach.