For Loops

Even though the while type of construct is very useful in a wide variety of situations, another iterative structure, the for statement, can be used to iterate across a range of values easily. A for statement allows us to write a loop that is executed a specific number of times.

::: {.activecode language=”cpp” sourcefile=”ForLoopIterations.cpp”} ForLoopIterations

#include <iostream> using namespace std;

int main() {

for (int i = 0; i < 10; i++){

cout << i << "hello world" << endl; }

} :::

In the example above, the hello world statement is executed 10 times.

A common use of the for construct is to implement certain repetition over a range of values.

::: {.activecode language=”cpp”} rangeForLoop1

#include <iostream> using namespace std;

// squares the numebers in range 5 // ex. 0*0, 1*1, 2*2 ... int main() { for (int i=0; i<5; i++) { cout << i*i << " "; }

return 0;

} :::

The code will use cout five times. The value of the variable i will start at 0 and go through the full sequence of values 0,1,2,3,4. This value is then squared and printed.

Check yourself

#include <iostream>
using namespace std;

int main() {

    for (int counter=0; counter<4; counter++) {
        cout << counter * 2 << " ";
    }

    return 0;
}

::: {.mchoice answer_a=”0 2 4 6” answer_b=”0 0 0 0” answer_c=”Runtime error” answer_d=”0 1 2 3” answer_e=”all of the above” correct=”a” feedback_a=”Good Job!” feedback_b=”Not quite, take another look at the operation happening in the cout line” feedback_c=”Not quite, take another look at the for loop” feedback_d=”Not quite, take another look at the operation happening in the cout line”} mc_forloop

Using the code above please select the answer that should appear? :::