Stage 1 · Code

Variables, Types & Control Flow

Basic Types

Learn Go's built-in value types — numbers, strings, booleans, and characters — and how to convert safely between them.

7 min readProgramming Foundations (Go)Code

Integer Types

Go has several integer types. The most common are int (platform-sized, usually 64-bit), int32, and int64. Use int by default unless you have a specific reason for a fixed size.

Gointeger-types-and-their-ranges.go

19 linesLn 1, Col 1Go

`int` and `uint` adapt to the platform. For most application code `int` is the right default. Use fixed-width types only when you need binary compatibility or specific range guarantees.

Type	Size	Range / Notes
int	Platform-sized (usually 64-bit)	Signed; use for general counting
int8 / int16 / int32 / int64	Fixed bit widths	When exact size matters
uint / uint8 / uint16 / uint32 / uint64	Unsigned variants	No negative values
byte	8-bit unsigned	Alias for uint8; raw binary data
rune	32-bit signed	Alias for int32; a Unicode code point

Floating-Point Types

Floating-point numbers represent real values with a decimal component. Go provides float32 and float64. Prefer float64 in almost all code — it has higher precision and is what most standard-library functions accept.

Gofloat64-in-everyday-use.go

20 linesLn 1, Col 1Go

The `0.1 + 0.2` result is expected floating-point behaviour. Use `fmt.Printf` with a format verb like `%.2f` to display rounded output.

Why 0.1 + 0.2 is not exactly 0.3

Floating-point numbers are stored in binary. Some decimal fractions cannot be represented exactly in binary, just as 1/3 cannot be represented exactly in decimal. This is not a Go bug; it is a property of IEEE 754 floating-point arithmetic used by virtually all programming languages.

string and rune

A string in Go is an immutable sequence of bytes, usually valid UTF-8 text. String literals appear in double quotes. A rune represents a single Unicode code point and is an alias for int32.

Gostrings,-bytes,-and-runes.go

28 linesLn 1, Col 1Go

Use `[]rune(s)` when you need to count visible characters in Unicode text. Use `len(s)` when you need the byte size of the string.

Strings are immutable

You cannot change a character in a Go string in place. To build or modify text, use strings.Builder, concatenation with +, or fmt.Sprintf. Strings are cheap to pass around because they are just a pointer and a length.

bool

A bool holds exactly two values: true or false. Go does not allow implicit conversions from integers or other types to bool. You must write an explicit comparison.

Gobool-values-and-conditions.go

19 linesLn 1, Col 1Go

In many languages `if count` would mean 'if count is not zero', but Go requires a real boolean expression. This makes conditions self-documenting.

Explicit Conversions

Go never silently converts between numeric types. You must write the conversion explicitly using the target type as a function call. This makes arithmetic intent visible and prevents hard-to-find bugs.

Gonumeric-conversions.go

20 linesLn 1, Col 1Go

To convert a number to its decimal string representation, use `fmt.Sprintf` or `strconv.Itoa`. `string(65)` gives the character 'A', not the text '65'.

string(number) is not what you expect

string(65) produces the string "A" because 65 is the Unicode code point for 'A'. Use strconv.Itoa(65) or fmt.Sprintf("%d", 65) to get the string "65".

Mark this lesson complete to store local progress and unlock a cleaner resume path the next time you visit.

Stage 1 · Code

Variables, Types & Control Flow

Basic Types

Learn Go's built-in value types — numbers, strings, booleans, and characters — and how to convert safely between them.

7 min readProgramming Foundations (Go)Code

Integer Types

Go has several integer types. The most common are int (platform-sized, usually 64-bit), int32, and int64. Use int by default unless you have a specific reason for a fixed size.

Gointeger-types-and-their-ranges.go

19 linesLn 1, Col 1Go

`int` and `uint` adapt to the platform. For most application code `int` is the right default. Use fixed-width types only when you need binary compatibility or specific range guarantees.

Type	Size	Range / Notes
int	Platform-sized (usually 64-bit)	Signed; use for general counting
int8 / int16 / int32 / int64	Fixed bit widths	When exact size matters
uint / uint8 / uint16 / uint32 / uint64	Unsigned variants	No negative values
byte	8-bit unsigned	Alias for uint8; raw binary data
rune	32-bit signed	Alias for int32; a Unicode code point

Floating-Point Types

Gofloat64-in-everyday-use.go

20 linesLn 1, Col 1Go

The `0.1 + 0.2` result is expected floating-point behaviour. Use `fmt.Printf` with a format verb like `%.2f` to display rounded output.

Why 0.1 + 0.2 is not exactly 0.3

string and rune

A string in Go is an immutable sequence of bytes, usually valid UTF-8 text. String literals appear in double quotes. A rune represents a single Unicode code point and is an alias for int32.

Gostrings,-bytes,-and-runes.go

28 linesLn 1, Col 1Go

Use `[]rune(s)` when you need to count visible characters in Unicode text. Use `len(s)` when you need the byte size of the string.

Strings are immutable

bool

A bool holds exactly two values: true or false. Go does not allow implicit conversions from integers or other types to bool. You must write an explicit comparison.

Gobool-values-and-conditions.go

19 linesLn 1, Col 1Go

In many languages `if count` would mean 'if count is not zero', but Go requires a real boolean expression. This makes conditions self-documenting.

Explicit Conversions

Gonumeric-conversions.go

20 linesLn 1, Col 1Go

To convert a number to its decimal string representation, use `fmt.Sprintf` or `strconv.Itoa`. `string(65)` gives the character 'A', not the text '65'.

string(number) is not what you expect

string(65) produces the string "A" because 65 is the Unicode code point for 'A'. Use strconv.Itoa(65) or fmt.Sprintf("%d", 65) to get the string "65".

Mark this lesson complete to store local progress and unlock a cleaner resume path the next time you visit.