Check out example codes for "range based for loop c++ with reference". It will help you in understanding the concepts better.

Code Example 1

for (<variable_declaration> : expression){
//statements
}

Code Example 2

1 #include <iostream>
2 #include <array>
3 #include <cstdlib>
4
5 using namespace std;
6
7 int main(){
8 array<int, 5> d = {1, 2, -1, 3, 5};
9 cout << "Items before modification: " << endl;
10 for (int item : d){
11 cout << item << " ";
12 }
13 //multiple elements of d by 3
14 for (int &itemRef : d){
15 itemRef *= 3;
16 }
17 cout << endl << "Items after modification: " << endl;
18 for (int item : d){
19 cout << item << " ";
20 }
21 cout << endl;
22 return 0;
23 }

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