Learn the basics of fn in Go language from scratch

Learn the basic knowledge of functions (fn) in Go language from scratch

As the popularity of Go language continues to rise in the programming field in recent years, more and more More developers began to learn and use Go language. In the process of learning Go language, function (fn) is a very important and basic concept. Mastering the basic knowledge of functions is very important for in-depth learning of Go language. This article will introduce the basic knowledge of functions in the Go language from scratch, and attach specific code examples to help beginners quickly master this knowledge.

First of all, we need to understand the definition and declaration of functions in the Go language. In the Go language, the definition of a function is usually as follows:

func 函数名(参数列表) 返回值类型 {
    // 函数体
}

Among them, func is the keyword used to define a function in the Go language, indicating the beginning of the function; Function name is a user-defined function name, used to identify different functions; Parameter list contains the parameters of the function, and multiple parameters are separated by commas; Return value type represents The return value type of the function can be omitted if the function has no return value; Function body contains the specific implementation code of the function.

Next, let us illustrate the definition and declaration of functions through a simple example:

package main

import "fmt"

func add(x, y int) int {
    return x + y
}

func main() {
    result := add(10, 20)
    fmt.Println("10 + 20 =", result)
}

In the above example, we define a function named add A function that accepts two parameters of type int, x and y, and returns their sum. In the main function, we call the add function and output the calculation results.

In addition to ordinary functions, the Go language also supports functions with multiple return values. For example:

func swap(x, y int) (int, int) {
    return y, x
}

In the above example, we defined a function named swap, which accepts two parameters of type intx and y, and return their exchange values. In the Go language, a function can return multiple values ​​at the same time, which is achieved by enclosing multiple return value types in parentheses.

In addition to ordinary functions and multi-return value functions, the Go language also supports anonymous functions and closures. An anonymous function is a function that does not need to be explicitly defined and can be used directly in the code. A closure is a function value that also contains references to variables in the outer function. For example:

func compute(fn func(int, int) int, x, y int) int {
    return fn(x, y)
}

func main() {
    result := compute(func(x, y int) int {
        return x * y
    }, 10, 20)
    fmt.Println("10 * 20 =", result)
}

In the above example, we define a function named compute, which accepts a parameter of function type fn, and calls the function to perform calculations. In the main function, we use an anonymous function as a parameter to pass to the compute function to implement a simple multiplication calculation.

In the Go language, functions also support passing a variable number of parameters. For example:

func sum(nums ...int) int {
    total := 0
    for _, num := range nums {
        total += num
    }
    return total
}

In the above example, we have defined a function called sum that accepts a variable number of int type parameters and calculates them of and. In the function body, we use the ... syntax to represent a variable number of parameters.

Through the above code examples, we briefly introduced the basic knowledge of functions in Go language, including function definition and declaration, multiple return value functions, anonymous functions and closures, variable number of parameters, etc. Functions are a very important concept in Go language and play a crucial role in learning and using Go language. I hope this article can help beginners better understand and master the basic knowledge of functions in Go language.

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