Add and subtract

Add and test the addition and subtraction functions.

Addition and subtraction functions

Now we will add two functions: add and subtract. Each takes two ints and returns an int.

In Dart a function is written as return_type name(parameters) { ... }. Example: int add(int a, int b) { return a + b; }.

For short single-line functions you can use the arrow (=>): int add(int a, int b) => a + b;. Both are the same.

Calling functions

You call the functions you defined inside main. Example: print(add(3, 4));. This prints the result of add(3, 4) (7) to the screen.

You can make multiple calls. print(add(3, 4)); and print(subtract(10, 3)); on separate lines give different results.

Functions prevent code repetition. If you add in five places, you call add five times; the addition logic stays in one place.

Exercise Add add and subtract

Add the functions int add(int a, int b) => a + b; and int subtract(int a, int b) => a - b; to the program. Inside main write print(add(3, 4)) and print(subtract(10, 3)).

Show example solution

void main() {
  print('Calculator ready');
  print(add(3, 4));
  print(subtract(10, 3));
}

int add(int a, int b) => a + b;
int subtract(int a, int b) => a - b;

Test yourself

Which is a correct Dart function definition?
```
int add(int a, int b)
```
- add(a, b) { }
- func add(int a, int b) { }
- int add(int a, int b) { }
- def add(a, b):
Show answer

int add(int a, int b) { } — Return type + name + parameters + block.

Second parameter

int add(int a, ____ b) => a + b;

Show answer

int add(int a, int b) => a + b;

Function concepts

add

Addition
subtract

Subtraction
int

Return type
=>

Arrow

Next lesson: Multiply and divide

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies