C++ Range-Based For Loop (C++11)

The range-based for loop in C++11 allows iterating over all elements of a container, array, or collection without explicitly managing indices or iterators.

1. Basic Range-Based For Loop Example

This example iterates through an array of integers using the range-based for loop.

#include <iostream>
using namespace std;

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

2. Using With Containers

Range-based for loops work with standard containers like vector, list, or array.

#include <iostream>
#include <vector>
using namespace std;

int main() {
    vector<int> v = {10, 20, 30};
    for (int x : v) {
        cout << x << endl;
    }
    return 0;
}

3. Common Mistakes

A common mistake is modifying elements without using references. Use & to modify container elements safely.

#include <iostream>
#include <vector>
using namespace std;

int main() {
    vector<int> v = {1, 2, 3};
    for (int &x : v) { // Use reference to modify
        x *= 2;
    }
    for (int x : v) {
        cout << x << endl;
    }
    return 0;
}

Conclusion

C++ range-based for loops simplify iteration over arrays and containers, making code cleaner and reducing errors. Use references when you need to modify elements.