How to print in golang

Use the function in the fmt package to print

The Go language is a statically typed, compiled language developed by Google. Its syntax is concise and clear, and its concurrency capabilities are powerful, so it has attracted much attention in recent years. . There are many built-in functions in the Go language, including printing functions. In this article, we will learn how to print using functions of fmt package in Go language.

1. fmt package

In the Go language, the fmt package is a very powerful package that implements the function of formatted input and output. The fmt package can easily perform printing operations. It can print values ​​of various data types and also set formats. The fmt package also provides some other functions such as Scan, Scanln and Scanf for reading data from standard input. Let's take a look at how to use the functions of the fmt package for printing.

2. The Print function in the fmt package

The Print function in the fmt package can print data to the standard output. The code below shows how to use the Print function to print a string to the console.

package main

import "fmt"

func main() {
   fmt.Print("Hello, world!")
}

In the above code, the Print function of the fmt package is called and the string "Hello, world!" is printed to the console. The printing here will not automatically wrap at the end. If you want to add a newline character at the end, you can use the println function.

package main

import "fmt"

func main() {
   fmt.Println("Hello, world!")
}

3. The Printf function in the fmt package

The Printf function of the fmt package can print a formatted string to the standard output. The first parameter of the Printf function is the format string, and the subsequent parameters are the content to be filled. The code below demonstrates how to print a formatted string using the Printf function.

package main

import "fmt"

func main() {
   name := "Tom"
   age := 32
   fmt.Printf("My name is %s，I'm %d years old.", name, age)
}

In the above code, the formatted string in sprintf is "My name is %s, I'm %d years old.", where the % character is followed by a letter, indicating this string The type of data that needs to be populated. For example, %s represents the string type, and %d represents the integer type. In this example, the first %s will be replaced by the value of the string variable name, and the second %d will be replaced by the value of the integer variable age.

4. Other functions in the fmt package

There are other functions in the fmt package, such as Sprintf function, Fprint function and Fprintf function. They are similar to Print and Printf functions, but use The method or output target is different. Below we briefly introduce these functions.

1. Sprintf function

. The Sprintf function is similar to the Printf function, but it does not output a formatted string to the console, but returns a string. The code below demonstrates how to use the Sprintf function.

package main

import "fmt"

func main() {
   name := "Tom"
   age := 32
   // 将格式化字符串保存到变量str中
   str := fmt.Sprintf("My name is %s，I'm %d years old.", name, age)
   // 输出变量str中的字符串
   fmt.Print(str)
}

2. Fprint function

The first parameter of the Fprint function is an io.Writer (interface), indicating the output destination. It can output formatted strings to files, network connections, standard output, etc., just pass in the appropriate io.Writer. For example, the following code demonstrates how to output a formatted string to a file.

package main

import (
    "fmt"
    "os"
)

func main() {
    f, err := os.Create("test.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer f.Close()
    // 将格式化字符串输出到文件中
    fmt.Fprint(f, "Hello, world!")
}

In the above code, the os.Create function creates a file named test.txt, and the formatted string "Hello, world!" is written to this file.

3. Fprintf function

The Fprintf function is similar to the Printf function, but it does not output the formatted string to the console, but outputs it to a file or network Connections, standard output, etc. locations. Similar to the Fprint function, you just need to pass in the appropriate io.Writer. The code below demonstrates how to output a formatted string to a file.

package main

import (
    "fmt"
    "os"
)

func main() {
    f, err := os.Create("test.txt")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer f.Close()
    name := "Tom"
    age := 32
    // 将格式化字符串输出到文件中
    fmt.Fprintf(f, "My name is %s，I'm %d years old.", name, age)
}

In the above code, the fmt.Fprintf function outputs the formatted string to the file, and the variables in the formatted string "My name is %s, I'm %d years old." are replaced with corresponding values.

Summary:

In the Go language, the functions of the fmt package can easily perform printing operations. They can print values ​​of various data types and can also perform formatting operations. By using some other functions, such as Sprintf function, Fprint function and Fprintf function, the output content can be made more flexible and diverse. Proficient in the functions in the fmt package can enable us to develop Go language programs more effectively.

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