Foreach loop

Foreach loop is used to iterate over the elements of the collection. The collection may be an array or a list. Foreach loop iterates through each element present inside array hence it is called as foreach loop. Foreach loop will only work on collection of values. Foreach loop in C++ or more specifically, range-based for loop was introduced with the C++ 11.

Syntax
for(datatype varName : ArrayName) {
    // code to be executed
}

CODE

EG 1 . Creating an array called musical instruments and printing out all elements in console using foreach loop

#include <iostream>
using namespace std;
int main() {
    string musicalInstruments[] = { "piano", "guitar", "violin", "drums" };
    for (string musicalInstrument : musicalInstruments) {
        cout << musicalInstrument << endl;
    }
}

OUTPUT
piano
guitar
violin
drums

CODE EXPLANATION
In the above code, foreach loop will loop through all the element present inside musicalInstruments(plural Name) array. Assume string musicalInstrument(singular Name) present inside foreach loop as somewhat like a variable. Now foreach loop will take the first element "piano" and store it inside musicalInstrument. Now system will enter inside foreach loop and print out piano in console. Now the loop will be iterated for second time where 2nd element "guitar" present inside musicalInstruments array will be taken and stored inside musicalInstrument variable and that will also be printed out in console. Now loop will be iterated for the 3rd time with 3rd element. In the same way foreach loop will loop through all the element present inside musicalInstruments array and print out values in console. Foreach loop will be automatically terminated when all the elements present inside array were looped.


EG 2 . Calculating total number of '$' present inside char[] using foreach loop

#include <iostream>
using namespace std;
int main() {
    char symbols[] = { '@', '$', '%', '&', ')', '(', '$', ')', 'P', '8', '$', '%' };
    int dollerCount = 0;
    for (char symbol : symbols) {
        //Inside if statement, if you going to have only one line of code then there is no need to use { and }
        if (symbol == '$') dollerCount++;
    }
    cout << "The number of $ present inside array is " << dollerCount << endl;
}

OUTPUT
The number of $ present inside array is 3

CODE EXPLANATION
In the above code, there is a char[] with collection of characters. Our goal here is to find how many doller character($) present inside that array. We used foreach loop here to loop through all the characters present inside symbols array. Each element will be looped and that value will be stored inside symbol variable. We set a condition using if statement to check whether that symbol is $ or not. If that symbol is doller, dollerCount variable value will be incremented by 1. So in the end of foreach loop the final value stored inside dollerCount is the total number of doller present inside Symbols array.


Exercises
1. Create a int[] with 20 elements. Print out only odd numbers present inside it.
2. Create a int[] with 20 elements. Print out only even numbers present inside it.
3. Create a int[] with 20 elements. Print out only prime numbers present inside it.


(Click Here, For more exercises)