How to Safely Set an Int Pointer to an Int Value in Go?

Setting an Int Pointer to an Int Value in Go

In Go, pointers are variables that store the address of another variable. They allow you to indirectly access the value of the referenced variable by dereferencing them using the * operator.

However, when working with pointers, you may encounter issues if you attempt to dereference a nil pointer. This is because a nil pointer has not been assigned to point to any valid memory location.

Consider the following code:

package main

import (
    "fmt"
    "reflect"
)

func main() {
    var guess *int
    fmt.Println(reflect.TypeOf(guess))
    *guess = 12345
    fmt.Println(guess)
}

This code attempts to set the value of the *guess pointer to 12345. However, this will result in a runtime panic due to an illegal memory address or nil pointer dereference.

The reason for this error is that the guess pointer is nil by default. When you try to dereference a nil pointer, the program will crash.

To fix this issue, you need to first assign the pointer to a valid memory location. You can use the builtin new() function to create a new int variable and assign its address to the guess pointer:

var guess *int
guess = new(int)
*guess = 12345

Now, the guess pointer points to a valid int variable, and you can safely dereference it to set or get its value.

Another way to assign a value to a pointer is by using the & operator to obtain the address of an existing variable:

value := 12345
guess := &value

Here, the guess pointer now points to the value variable. Any changes made to the pointed value through the guess pointer will also affect the original value variable.

By understanding the concept of nil pointers and how to assign them to valid memory locations, you can effectively use pointers in your Go programs to indirectly access and manipulate data.

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