Introduction
In C++, arrays are a fundamental data structure used to store multiple elements of the same data type. When working with arrays, it's essential to know the size or length of the array to perform various operations efficiently.
In this article, we'll learn different methods to find the size of an array in C++, including counting elements, using begin() & end() functions, the sizeof() function, the size() function in STL, & pointers.
Ways to Find the Length of an Array in C++
Counting Each Element
One straightforward method to determine the size of an array in C++ is by counting each element. This involves using a loop to iterate through the array & incrementing a counter until the end of the array is reached. This method is particularly useful when the array does not have a predefined size or when using arrays that are not null-terminated.
Here's how you can implement this method:
- C++
C++
#include <iostream>
using namespace std;
int main() {
int myArray[] = {5, 10, 15, 20, 25}; // An array of integers
int count = 0; // Counter for the array elements
// Loop to count elements
for(int i = 0; myArray[i]; i++) {
count++;
}
cout << "Number of elements in the array: " << count << endl;
return 0;
}
Output
Number of elements in the array: 9
In this example, the loop continues until it has iterated through each element of the array, increasing the count by one on each iteration. This method is simple but becomes less efficient as the size of the array increases.
Using begin() & end() Functions
Another method to find the size of an array involves using the begin() & end() functions provided by C++. These functions offer a way to obtain iterators pointing to the beginning & end of the array, respectively. The distance between these two iterators represents the size of the array.
Example of using begin() & end():
- C++
C++
#include <iostream>
#include <iterator> // For std::begin() & std::end()
using namespace std;
int main() {
int myArray[] = {5, 10, 15, 20, 25, 30};
// Calculate the size using std::begin() & std::end()
int size = distance(begin(myArray), end(myArray));
cout << "The array has " << size << " elements." << endl;
return 0;
}Output
The array has 6 elements.
This method is not only straightforward but also safe & effective, especially for arrays where the length is not directly known or specified.
sizeof() Function
The sizeof() function in C++ can also be used to find the size of an array. This function returns the total byte size of the array. To find the number of elements, you divide this by the size of one element in the array.
Here’s an example:
- C++
C++
#include <iostream>
using namespace std;
int main() {
int myArray[] = {5, 10, 15, 20, 25, 30, 35};
// Calculate the size using sizeof()
int size = sizeof(myArray) / sizeof(myArray[0]);
cout << "The array has " << size << " elements." << endl;
return 0;
}Output
The array has 7 elements.
This approach provides a quick & reliable way to determine the size of the array when the data type of the array elements is known.
46+ registered 