C++ Arrays and Loops
Arrays and loops are a natural pair. Instead of writing a separate line for every element, you can use a loop to walk through the whole array in just a few lines. This becomes essential as arrays grow larger.
Looping Through an Array
A classic for loop uses a counter variable as the index. You start at 0 and keep going while the counter is less than the number of elements, increasing the counter by one each time.
Printing every element with a for loop
#include <iostream>
using namespace std;
int main() {
int myNumbers[5] = {10, 20, 30, 40, 50};
for (int i = 0; i < 5; i++) {
cout << myNumbers[i] << "\n";
}
return 0;
}
// Output: 10 20 30 40 50 (each on its own line)The Range-Based For Loop
Modern C++ offers a cleaner way to loop through an array without managing an index at all. The range-based for loop copies each element into a variable so you can use it directly. It is easier to read and avoids off-by-one mistakes.
A range-based for loop
#include <iostream>
using namespace std;
int main() {
int myNumbers[5] = {10, 20, 30, 40, 50};
for (int number : myNumbers) {
cout << number << "\n";
}
return 0;
}
// Output: 10 20 30 40 50 (each on its own line)Getting the Array Size
In modern C++ you can find how many elements an array has with sizeof(array) / sizeof(array[0]). This divides the total memory the array uses by the memory of a single element. Using it in the loop condition means you do not have to hard-code the size.
- sizeof(myNumbers) gives the total bytes used by the whole array.
- sizeof(myNumbers[0]) gives the bytes used by one element.
- Dividing the two gives the element count, which is safer than typing a number by hand.
