24sp ver.

Note: this is for the Spring 2024 iteration of CSE 121. Looking for a different quarter? Please visit https://courses.cs.washington.edu/courses/cse121/.

## Relational and Logical Operators¶

(evaluate expressions as true or false)

#### Example

``````if (num < 0) {
System.out.println("Negative!!");
} else if (num <= 5) {
System.out.println("I'm small.");
} else {
System.out.println("I'm big.");
}
``````

### Relational Operators¶

Operator Description
`<` less than
`<=` less than or equal
`>` greater than
`>=` greater than or equal
`==` equal
`!=` not equal

### Logical Operators¶

Operator Description
`&&` and
`||` or
`!` not

## Conditionals and Conditional Statement Structures¶

(changing execution of program depending on values)

### If Conditional Statement¶

Use case: Want to execute a certain block of statement(s) in one particular case.

#### Pattern

``````if (condition) {
// code block - executed if condition is true
}
``````

#### Example

``````int num = 5;
if (num < 10) {
System.out.println("num is smaller than 10!");
}
``````

#### Output

``````num is smaller than 10!
``````

### If/Else Conditional Statement¶

Use case: Use when dealing with one or two cases (“this OR that!”).

#### Pattern

``````if (condition) {
// code block - executed if condition is true
} else {
// code block - executed if condition is false
}
``````

#### Example

``````int num = 12;
if (num < 10) {
System.out.println("num is smaller than 10!");
} else {
System.out.println("num is larger or equal to 10!");
}
``````

#### Output

``````num is larger or equal to 10!
``````

### If/Else-if Conditional Statement¶

Use case: Want to evaluate specific cases, not just one or the other.

#### Pattern

``````if (condition1) {
// code block - executed if condition1 is true
} else if (condition2) {
// code block - executed if condition2 is true (and if condition1 is false)
}
``````

#### Example

``````int num = 10;
if (num < 10) {
System.out.println("num is smaller than 10!");
} else if (num == 10) {
System.out.println("num is equal to 10!");
}
``````

#### Output

``````num is equal to 10!
``````

### If/Else-if/Else Conditional Statement¶

Use case: Use when you want to evaluate specific cases along with including a default case (“this OR this OR that!”).

#### Pattern

``````if (condition1) {
// code block - executed if condition1 is true
} else if (condition2) {
// code block - executed if condition2 is true (and if condition1 is false)
} else {
// code block - executed if all conditions are false
}
``````

#### Example

``````int num = 12;
if (num < 10) {
System.out.println("num is smaller than 10!");
} else if (num == 10) {
System.out.println("num is equal to 10!");
} else {
System.out.println("num is larger than 10!");
}
``````

#### Output

``````num is larger than 10!
``````

### If and If Conditional Statements¶

Use case: Want to evaluate multiple blocks of statements based on specific test cases.

#### Pattern

``````if (condition1) {
// code block - executed if condition1 is true
}

if (condition2) {
// code block - executed if condition2 is true
}
``````

#### Example

``````int num = 5;
if (num < 10) {
System.out.println("num is smaller than 10!");
}
if (num < 2) {
System.out.println("num is smaller than 2!");
}
``````

#### Output

``````num is smaller than 10!
``````