Loops

Loops in C++

C++ has all the loops from C — for, while, do-while — plus a powerful C++11 addition: the range-based for loop.

Traditional for Loop

for (int i = 0; i < 5; i++) {
    cout << i << endl;
}

while Loop

int n = 1;
while (n <= 10) {
    cout << n << " ";
    n *= 2;
}
cout << endl;
// 1 2 4 8

Range-Based for Loop

C++11 introduced a cleaner syntax for iterating over collections:

#include <vector>
using namespace std;

vector<int> nums = {10, 20, 30, 40};
for (int n : nums) {
    cout << n << endl;
}

Use const string& for strings to avoid copying:

vector<string> names = {"Alice", "Bob", "Carol"};
for (const string& name : names) {
    cout << "Hello, " << name << endl;
}

break and continue

break exits the loop; continue skips to the next iteration:

for (int i = 0; i < 10; i++) {
    if (i == 3) continue;  // skip 3
    if (i == 7) break;     // stop at 7
    cout << i << " ";
}
// 0 1 2 4 5 6

Nested Loops

for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        cout << i * j << " ";
    }
    cout << endl;
}

Your Task

1. Use a for loop to print 1 2 3 4 5 on one line (space-separated, no trailing space)
2. Use a range-based for loop to print each language in {"C", "C++", "Go"} on its own line