1. CS111 Lab
while loops
Instructor: Michael Gordon

2. Repeating instructions
 To repeat a set of instructions, we can use
a while loop, which checks a condition
(like an if statement) and continues as
long as the condition is true.
 while (condition to check){
instructions;
}

3. A word of advice
 If the while loop checks a certain variable,
make sure that:
 A) The variable has a value before the loop
starts.
 B) That variable can change inside the loop.
 x = 1;
 while (x<5){“output”} will never end
 while (x<5) {x++; “output”} will stop once x is 5.

4. Incrementing
 Incrementing (+1) and decrementing (-1)
are useful tools for iterating in loops.
 int x = 0;
 x++; //means x = x+1; called post-increment
 ++x; // means x = x+1; called pre-increment
 x+=1; // means x = x+1;
 Decrementing:
 --x;
 x--;