Conditional Statements (If/Else)

If Statements

If statements only run code within a coding block when certain conditions are true.

Format:

Almost everything but Python:

if (test) {
    // Run this code if test is true
}

Example:

if (num < 4) {
    println("This number is less than 4!");
}

Python:

Indentation is the only way Python recognizes the code block. Double-check the number of indents if the code has errors or does not work.

if test:
    # Run this code if test is true

Example:

if num < 4:
    println("This number is less than 4!")

If/Else Statement

If/else statements only run code within a coding block when certain conditions are true, otherwise the else statement block of code will run.

Format:

Almost everything but Python:

if (test) {
    // Run this code if test is true
}
else {
    // Otherwise run this code
}

Example:

if (num < 4) {
    println("This number is less than 4!");
}
else {
    println("This number is 4 or higher ... or not a number at all!");
}

Python:

Indentation is the only way Python recognizes the code block. Double-check the number of indents if the code has errors or does not work.

if test:
    # Run this code if test is true
else:
    # Otherwise run this code

Example:

if num < 4:
    println("This number is less than 4!")
else:
    println("This number is 4 or higher ... or not a number at all!")

If/Else If/Else Statement

If/else if/else statements only run code within a coding block when certain conditions are true, otherwise the else statement block of code will run.

Else if statement blocks go between if and the else blocks to provide more options.

These are good for multiple specific choices .

Format:

Almost everything but Python:

if (test) {
    // Run this code if test is true
}
else if (test2) {
    // Run this code if the past tests are false and this test is true
}
else {
    // Otherwise run this code
}

Example:

if (num < 4) {
    println("This number is less than 4!");
}
else if (num > 7) {
    println("This number is greater than 7!");
}
else {
    println("This number is 4 or higher ... or not a number at all!");
}

Python:

Indentation is the only way Python recognizes the code block. Double-check the number of indents if the code has errors or does not work.

if test:
    # Run this code if test is true
elif test2:
    # Run this code if the past tests are false and this test is true
else:
    # Otherwise run this code

Example:

if num < 4:
    println("This number is less than 4!")
elif num > 7:
    println("This number is greater than 7!")
else:
    println("This number is 4 or higher ... or not a number at all!")

Switch/Case Statement

This doesn't exist in certain languages.

Switch/case statements replace else if statements when equivalents are being tested .

Instead of testing in the parentheses, the parentheses hold the first value , then each “case” is what the variable is compared with . If the variable matches the case, the corresponding code block runs .

Each case needs a “break” to move on .

Each switch/case code block should have a default case serving as an else statement . Programmers often use the default case to test if the block ran, but had no equivalents (a form of error catching)

Format:

Almost everything but Python:

switch (variable) {
    case caseValue:
        // runs if the case is equivalent to caseValue
        break;
    case caseValue2:
        // runs if the case is equivalent to caseValue2
        break;
    default:
        // runs if all caseValues are not true
        break;
}

Example:

String name = "Nina";

switch (name) {
    case "Andrew":
        println("Andrew has three cats.");
        break;
    case "Nina":
        println("Dina dances.");
        break;
    default:
        println("Please choose either 'Andrew' or 'Dina'.");
        break;
}