Go Integer Data Type - Go Tutorial

In Go, integer data types are used to represent numbers without decimal points, like 150, -72, or 100000.

Integer data types are classified into two main categories:

Signed Integers
These integers can store both positive and negative values.
Unsigned Integers
These integers are restricted to storing only non-negative values.

Note: If you don’t specify an integer type explicitly, the default type is int.

Signed Integers

Signed integers are declared using one of the int keywords and can hold values that are either positive or negative.

Example: Declaring Signed Integers

package main

import ("fmt")

func main() {
    var engineCapacity int = 1200   // Signed integer (positive)
    var fuelEfficiency int = -20   // Signed integer (negative)

    fmt.Printf("Type: %T, value: %v\n", engineCapacity, engineCapacity)
    fmt.Printf("Type: %T, value: %v\n", fuelEfficiency, fuelEfficiency)
}

Go
​x
 
package main​import ("fmt")​func main() {    var engineCapacity int = 1200   // Signed integer (positive)    var fuelEfficiency int = -20   // Signed integer (negative)​    fmt.Printf("Type: %T, value: %v\n", engineCapacity, engineCapacity)    fmt.Printf("Type: %T, value: %v\n", fuelEfficiency, fuelEfficiency)}​

Output:

Type: int, value: 1200  
Type: int, value: -20

Go
 
Type: int, value: 1200  Type: int, value: -20  ​

Types of Signed Integers in Go

Type	Size	Range
`int`	Depends on platform:	-2147483648 to 2147483647 (32-bit systems)
	32-bit or 64-bit	-9223372036854775808 to 9223372036854775807 (64-bit systems)
`int8`	8 bits / 1 byte	-128 to 127
`int16`	16 bits / 2 bytes	-32768 to 32767
`int32`	32 bits / 4 bytes	-2147483648 to 2147483647
`int64`	64 bits / 8 bytes	-9223372036854775808 to 9223372036854775807

Unsigned Integers

Unsigned integers are declared using one of the uint keywords and can store only non-negative values.

Example: Declaring Unsigned Integers

package main

import ("fmt")

func main() {
    var bikePrice uint = 1500000   // Unsigned integer (positive only)
    var insuranceFee uint = 25000 // Unsigned integer (positive only)

    fmt.Printf("Type: %T, value: %v\n", bikePrice, bikePrice)
    fmt.Printf("Type: %T, value: %v\n", insuranceFee, insuranceFee)
}

Go
 
package main​import ("fmt")​func main() {    var bikePrice uint = 1500000   // Unsigned integer (positive only)    var insuranceFee uint = 25000 // Unsigned integer (positive only)​    fmt.Printf("Type: %T, value: %v\n", bikePrice, bikePrice)    fmt.Printf("Type: %T, value: %v\n", insuranceFee, insuranceFee)}​

Output:

Type: uint, value: 1500000  
Type: uint, value: 25000

Go
 
Type: uint, value: 1500000  Type: uint, value: 25000  ​

Types of Unsigned Integers in Go

Type	Size	Range
`uint`	Depends on platform:	0 to 4294967295 (32-bit systems)
	32-bit or 64-bit	0 to 18446744073709551615 (64-bit systems)
`uint8`	8 bits / 1 byte	0 to 255
`uint16`	16 bits / 2 bytes	0 to 65535
`uint32`	32 bits / 4 bytes	0 to 4294967295
`uint64`	64 bits / 8 bytes	0 to 18446744073709551615

Choosing the Right Integer Type

When selecting an integer type, consider the range of values the variable will store.

Example of Incorrect Type Assignment

This example demonstrates an error caused by assigning a value beyond the range of int8 (valid range is -128 to 127):

package main

import ("fmt")

func main() {
    var maxSpeed int8 = 300    // Out of range for int8
    fmt.Printf("Type: %T, value: %v\n", maxSpeed, maxSpeed)
}

Go
 
package main​import ("fmt")​func main() {    var maxSpeed int8 = 300    // Out of range for int8    fmt.Printf("Type: %T, value: %v\n", maxSpeed, maxSpeed)}​

Result:

./prog.go:5:7: constant 300 overflows int8

Go
 
./prog.go:5:7: constant 300 overflows int8​