What Is the Difference Between int, int32, and int64 in Go

The difference is that int is platform-dependent (32-bit on 32-bit systems, 64-bit on 64-bit systems), while int32 and int64 are fixed-width types regardless of the architecture. Use int for general counting and indexing, and use int32 or int64 when you need a specific size for binary protocols or file formats.

package main

import (
	"fmt"
	"unsafe"
)

func main() {
	fmt.Printf("int size: %d bits\n", unsafe.Sizeof(int(0))*8)
	fmt.Printf("int32 size: %d bits\n", unsafe.Sizeof(int32(0))*8)
	fmt.Printf("int64 size: %d bits\n", unsafe.Sizeof(int64(0))*8)
}

Think of int as a variable-sized box that changes size depending on your computer, while int32 and int64 are fixed-size boxes that never change. You use int for everyday tasks like counting loops, but you use the fixed sizes when you need to be sure the data takes up the exact same amount of space on every computer.