C While Loop
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.
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:
Note: Do not forget to increase the variable used in the condition
(i++), otherwise
the loop will never end!
The Do/While Loop
The do/while loop is a variant of the while loop. This loop will
execute the code block once, before checking if the condition is true, then it will
repeat the loop as long as the condition is true.
Syntax
do {
// code block to be executed
}
while (condition);
The example below uses a do/while loop. The loop will always be
executed at least once, even if the condition is false, because the code block
is executed before the condition is tested:
Do not forget to increase the variable used in the condition, otherwise the loop will never end!
Real-Life Examples
To demonstrate a practical example of the while loop, we can create a simple "countdown" program:
Example
int countdown = 3;
while (countdown > 0) {
printf("%d\n",
countdown);
countdown--;
}
printf("Happy New Year!!\n");
Try it Yourself »
To demonstrate a practical example of the while loop combined with an if else statement, let's say we play a game of Yatzy!
Example
Print "Yatzy!" If the dice number is 6:
int dice = 1;
while (dice <= 6) {
if (dice < 6) {
printf("No Yatzy\n");
} else {
printf("Yatzy!\n");
}
dice = dice + 1;
}
Try it Yourself »
If the loop passes the values ranging from 1 to 5, it prints "No Yatzy". Whenever it passes the value 6, it prints "Yatzy!".