Prerequisite: Pointers in Go
Pointers in Go programming language or Golang is a variable which is used to store the memory address of another variable. You can also pass the pointers to the function like the variables. There are two ways to do this as follows:
Create a pointer and simply pass it to the Function
In the below program we are taking a function ptf which have integer type pointer parameter which instructs the function to accept only the pointer type argument. Basically, this function changed the value of the variable x. At starting x contains the value 100. But after the function call, value changed to 748 as shown in the output.
Go
// Go program to create a pointer// and passing it to the functionpackage main import "fmt" // taking a function with integer// type pointer as an parameterfunc ptf(a *int) { // dereferencing *a = 748} // Main functionfunc main() { // taking a normal variable var x = 100 fmt.Printf("The value of x before function call is: %d\n", x) // taking a pointer variable // and assigning the address // of x to it var pa *int = &x // calling the function by // passing pointer to function ptf(pa) fmt.Printf("The value of x after function call is: %d\n", x) } |
Output:
The value of x before function call is: 100 The value of x after function call is: 748
Passing an address of the variable to the function call
Considering the below program, we are not creating a pointer to store the address of the variable x i.e. like pa in the above program. We are directly passing the address of x to the function call which works like the above-discussed method.
Go
// Go program to create a pointer// and passing the address of the// variable to the functionpackage main import "fmt" // taking a function with integer// type pointer as an parameterfunc ptf(a *int) { // dereferencing *a = 748} // Main functionfunc main() { // taking a normal variable var x = 100 fmt.Printf("The value of x before function call is: %d\n", x) // calling the function by // passing the address of // the variable x ptf(&x) fmt.Printf("The value of x after function call is: %d\n", x) } |
Output:
The value of x before function call is: 100 The value of x after function call is: 748
Note: You can also use the short declaration operator(:=) to declare the variables and pointers in above programs.
