Creating a Function

Parts of Creating a Function

1. Keyword that says the code block is a function

2. Function name

3. Parameters or “input” information

4. Actions to take

5. Return or “output” information

1. Keyword to say it’s a function

• If explicit languages, it’s often void or the data type of returned info/output expected

• For implicit languages, it’s usually function or def.

2. Name of the Function

• Naming a function is similar to naming a variable - they have NO SPACES.

• The names are often a verb or action .

• As for casing, it depends on the language but will work with any.

3. Parameters / Input

• Parameters are pieces of information needed for the work to be done inside the function.

• The names of the arguments serve as temporary variables usable only within the function.

• They are separated by commas and listed inside the parentheses ( ) .

• Like other variables, might need associated data types if the language is explicit.

4. Actions to Take

Just like other blocks of code, the code that should run should be put inside curly brackets { }.

5. Return or Output

• In explicit languages - especially if the function code starts with a data type - that data type must be “returned.”

• Use a line of code in the curly brackets: return value;

• The value should match the data type

• For some languages, void functions require return none;

Examples

Processing, Java, and C#:

// Function adds 3.5 to a provided number

float addThreeAndAHalf(float startNum) {
    return startnum + 3.5;
}

// Function prints "1, 2, 3"

void countToThree() {
    println("1, 2, 3");
}

JavaScript:

// Function adds 3.5 to a provided number

function addThreeAndAHalf(startNum) {
    return startnum + 3.5;
}

// Function prints "1, 2, 3"

function countToThree() {
    document.write("1, 2, 3");
}

Python:

# Function adds 3.5 to a provided number

def addThreeAndAHalf(float startNum):
    return startnum + 3.5
    
# Function prints "1, 2, 3"

def countToThree():
    println("1, 2, 3")