Range Based for Loop C++

Example of Range Based for loop C++

The range-based for loop simplifies iteration over elements in containers without explicit index manipulation or iterator declaration.

Example 1 - Ranged for loop using arrays

• C++

C++

#include <iostream>

int main() {
    int arr[] = {1, 2, 3, 4, 5};
    for (int num : arr) {
        std::cout << num << " ";
    }
    return 0;
}

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Explanation: This loop iterates over each element of the array arr, storing each element in the variable num, and then prints the value of num.

Example 2 - Ranged for loop using vector

• C++

C++

#include <iostream>
#include <vector>

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};
    for (int num : vec) {
        std::cout << num << " ";
    }
    return 0;
}

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Explanation: Similar to the array example, this loop iterates over each element of the vector vec and prints its value.

Example 3: Declare Collection inside the Loop

• C++

C++

#include <iostream>
#include <vector>

int main() {
    std::vector<std::vector<int>> matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
    for (auto& row : matrix) {
        for (int num : row) {
            std::cout << num << " ";
        }
        std::cout << std::endl;
    }
    return 0;
}

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Explanation: This loop demonstrates iterating over a 2D vector matrix, where each element is itself a vector. It iterates over each row of the matrix and then over each element in that row, printing them.

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Benefits of the Range-Based Loop

• It is easy to use and has a simple syntax.
   
• A range-based for loop does not involve calculating the number of variables in a container.
   
• It recognizes the beginning and end elements of the containers.
   
• We can easily change the size and elements of the container.
   
• The elements are not duplicated.
   
• It is way faster than the traditional for loop.
   
• The auto keyword is typically used to determine the data type of container elements.

Frequently Asked Questions 

In C++, what is a range-based for loop?

Since C++ 11, there has been a range-based for loop. It runs a for loop over a set of values. As a more readable alternative to traditional for loop, this function operates over a range of values, such as all elements in a block.

Is a range-based loop in C++ faster?

Since it caches the end iterator, uses pre-increment, and only dereferences the iterator once, range-for is as fast as possible. Then, while range-for may be slightly faster, there's no reason not to use it because it's also easier to write (when appropriate).

What is the difference between range-based for loop and normal for loop?

The range-based for loop simplifies iteration over elements in containers by abstracting index manipulation, compared to the traditional for loop.

What is a C++ iterator loop?

An iterator is a C++ Standard Library object that can iterate over elements in a container and provide access to individual elements.

What is the purpose of ‘auto’ in C++?

The auto keyword is a straightforward way to declare a variable with a complex type. We can use auto to declare a variable whose initialization expression contains templates, pointers to functions, or pointers to members.

Conclusion

In this blog, we studied the details of range based for loop C++. We have also covered C++ as a language, definition, and example of the topic: Range Based for loop C++.

To know about more articles like range based for loop C++, check out the following:

• Recursive Binary Search
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• Four Pillars of OOPS
   

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