The Go programming language uses the **`Errorf` function** to generate a customized error message. It supports custom format specifiers and uses a format string to format the output string.

To use this function, you must import the `fmt` package in your file and access the `Errorf` function within, using the `.` notation: `fmt.Errorf`. 

Here, `Errorf` is the actual function, while `fmt` is the Go package that stores the definition of this function.

# Function definition

The definition of the `Errorf` function inside the `fmt` package is as follows:


# Parameters
The `fmt.Errorf` function takes two parameters, described below:

* **`format`**: This argument is of type string and represents the string containing custom specifiers that the `Errorf` uses to format the final output error.

* **`a ...interface{}`**: This is the list of all arguments that replace specifier values in the format string to generate the final error message. There can be any number of input arguments and of any type.

# Common specifiers

The following is a table of the most commonly used format specifiers in Go and their descriptions.


| Specifiers  | Description   |
|---|---|
| `%s`   | To print a string  |
| `%d`   | To print an integer|
| `%v ` | To print values of all elements in a structure  |
|` %+v`  | To print the names and values of all elements in a structure  |

# Return values

The `fmt.Errorf` function returns the final error message, generated using the format string and the list of arguments. This output is of type error.

## Examples
The following example is a simple program. We first initialize a variable with a string and use it with a format string to generate an error message that we then print out using the `println` function. 

package main
  
import (
    "fmt"
)
  
func main() {

    quantity := 500
    unit := "meters"


    err := fmt.Errorf("The workshop is less that %d %s",quantity, unit)

    fmt.Println(err)
}

Since the error message that is generated by the `Errorf` function is of type `error`, you can also use the `Error` method to access it. This is shown in the following example:

package main
  
import (
    "fmt"
)
  
func main() {
    
    organization := "Educative"

    my_err := fmt.Errorf("Hello and welcome to %s", organization)

    fmt.Println(my_err.Error())
}

What is the golang Errorf function?

Go's Errorf function in the fmt package generates custom error messages using format strings and specifiers.

Specifiers	Description
`%s`	To print a string
`%d`	To print an integer
`%v`	To print values of all elements in a structure
`%+v`	To print the names and values of all elements in a structure