Flash cards
Review the key moves
What is the main idea behind C++ While Loop?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ ( condition ) {Put the learning moves in the order that makes the concept easiest to apply.
C++ Loops
Loops can execute a block of code as long as a specified condition is reached.
Loops are handy because they save time, reduce errors, and they make code more readable.
C++ While Loop
The while loop loops through a block of code as long as a specified condition is true :
Syntax
while ( condition ) {
// code block to be executed
}In the example below, the code in the loop will run, over and over again, as long as a variable ( i ) is less than 5:
Example
int i = 0;
while (i < 5) {
cout << i << "\n";
i++;
}Note
Do not forget to increase the variable used in the condition ( i++ ), otherwise the loop will never end!
Do you wonder why we use the letter i as a variable name? It's a counter variable and a common choice in simple loops because it's short, traditional, and stands for 'index' or 'iterator'.
Countdown Example
This example counts down from 3 to 1 and then displays "Happy New Year!!" at the end:
Example
int countdown = 3;
while (countdown > 0) {
cout << countdown
<< "\n";
countdown--;
}
cout << "Happy New Year!!\n";