For Loop

Overview

For loops are used when the number of iterations is known. Range-based for loops (C++11) provide a safer, cleaner syntax for iterating over arrays and STL containers.

Syntax

cpp

// Standard for loop (Initialization; Condition; Update)
for (int i = 0; i < 5; i++) {
    cout << i << " ";
}

// Range-based for loop (C++11)
int arr[] = {10, 20, 30};
for (int val : arr) {
    cout << val << " "; // Read-only iteration
}

// Range-based by reference (allows modification)
for (int& val : arr) {
    val *= 2; 
}

Common Pitfalls

Off-by-one errors in standard for loops (e.g., using `<=` instead of `<` when accessing array indices).

Interview Tips

Always use range-based for loops over standard for loops when iterating over an entire container. It prevents 'off-by-one' bounds errors.
Understand why `for (const auto& item : container)` is the most efficient and safe way to iterate over complex objects.

Real-World Example

Using range-based for loop with `auto` keyword.

example

cpp

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

int main() {
    vector<string> names = {"Alice", "Bob", "Charlie"};
    
    for (const auto& name : names) {
        cout << "Hello, " << name << "!\n";
    }
    return 0;
}

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