1. CS111 Lab
Decisions, Decisions
Instructor: Michael Gordon

2. If statements
 Structure of if statement:
 if (true or false to check) {
instruction or output;
}
OR (if only one instruction:
 if (true or false to check) instruction or
output;

3. Common Checks
 x>y “x is greater than y?”
 x<y “x is less than y?”
 x==y “x is equal to y?”
 x!=y “x is not equal to y?”
 x>=y “x is greater than or equal to y?”
 x<=y “x is less than or equal to y?”
 x%2==0 “x is divisible by two (even).”

4. Using else
 if (true or false to check) {
instruction or output;
}
else {
instruction or output;
}

5. else if
 if (true or false to check) {
instruction or output;
}
else if (another check) {
instruction or output;
}
else {
instruction or output;
}

6. Compound Comparisons
 Use parentheses if clarity is needed.
 Use && for AND and || for OR.
 Examples:
if (x>0 && x<100) “x is greater than 0 and
less than 100.”
If (x<0 || x>100) “x is less than 0 or greater
than 100.”

7. Negation
 You can also check the opposite value of
a condition using !
 Example:
 if (!(x%2==0)) “x is odd (not even).”