Integer types

Learn int and num types.

int and num types

In Dart integers are stored in the int type. An int holds a 64-bit integer; the range is about ±9 billion billion. Plenty for everyday calculations.

To declare an int write int age = 25;. You can print it with print(age);.

num is the common supertype of int and double. So a num variable can hold both integers and decimals. But in most cases you use int or double explicitly.

Exercise int variable

Declare an integer variable with int age = 25; and print it with print(age);.

Show example solution

void main() {
  int age = 25;
  print(age);
}

num supertype

num is the common parent of int and double. A num variable can hold an int first, then a double.

For example num x = 5; works; then x = 5.5; is also valid. Both are subtypes of num.

In practice num is rarely used; writing int or double explicitly is clearer. num appears mostly in math function signatures.

Test yourself

Integer type
```
____ age = 25;
```
Show answer
```
int age = 25;
```
How many bits is int in Dart?
- 16 bit
- 32 bit
- 8 bit
- 64 bit
Show answer

64 bit — This allows large numbers.
Match the types

int

Integer
num

Number supertype
double

Floating-point
var

Type inference

Next lesson: Floating-point types

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