In-depth understanding of Golang formatting placeholders

Golang is a very popular programming language, and its formatted placeholders are often used in daily development. An in-depth understanding of Golang formatting placeholders allows us to better control the output format and improve the readability and maintainability of the code. This article will introduce in detail the commonly used formatting placeholders in Golang, as well as specific code examples to help readers better understand.

1. Basic formatting placeholders

In Golang, the fmt package provides the function of formatting output. The most commonly used placeholders are as follows Several:

• %v: The default format of the value.
• %T: Type of value.
• %d: decimal integer.
• %f: floating point number.

The following is a simple sample code that demonstrates the use of these basic formatting placeholders:

package main

import "fmt"

func main() {
    var i = 10
    var f = 3.14

    fmt.Printf("整数 i 的值为：%d
", i)
    fmt.Printf("浮点数 f 的值为：%f
", f)
    fmt.Printf("i 的值为：%v，类型为：%T
", i, i)
}

By running the above code, we can see the output results As follows:

整数 i 的值为：10
浮点数 f 的值为：3.140000
i 的值为：10，类型为：int

2. Width and precision control characters

In addition to basic formatting placeholders, width and precision control characters can also be used in Golang. Controls the format of the output. The following are some commonly used control characters:

• ]: Specify the width of the output to be 5 characters, and fill the insufficient part with spaces.
• %.2f: Keep two decimal places.
• %8.2f: Keep two decimal places, the total width is 8 characters.

The following sample code shows how to use these control characters:

package main

import "fmt"

func main() {
    var i = 10
    var f = 3.14159

    // 控制输出的宽度和精度
    fmt.Printf("整数 i 的值为：%5d
", i)
    fmt.Printf("浮点数 f 的值为：%.2f
", f)
    fmt.Printf("浮点数 f 的值为：%8.2f
", f)
}

Run the above code, the output result is as follows:

整数 i 的值为：   10
浮点数 f 的值为：3.14
浮点数 f 的值为：    3.14

3. Alignment Mode control

In Golang's formatting placeholder, you can also control the alignment through the - symbol, 0 symbol and space symbol. The following are some commonly used alignment control characters:

• %-5d: Left aligned, the output width is 5 characters.
• d: Fill with 0, the width of the output is 5 characters, right justified.
• %5s: Right-justified, the width of the output is 5 characters, and the insufficient part is filled with spaces.

The following sample code shows how to use the alignment control character:

package main

import "fmt"

func main() {
    var i = 10
    var str = "hello"

    // 控制对齐方式
    fmt.Printf("整数 i 的值为：%-5d
", i)
    fmt.Printf("字符串 str 的值为：%5s
", str)
    fmt.Printf("整数 i 的值为：%05d
", i)
}

Run the above code, the output result is as follows:

整数 i 的值为：10   
字符串 str 的值为: hello
整数 i 的值为：00010

The above is about the Golang format It provides some basic introduction and sample code of placeholders. Readers can gain an in-depth understanding of these contents and flexibly use them in their own code to achieve better output effects. I hope this article can help readers better understand Golang's formatting placeholders.

The above is the detailed content of In-depth understanding of Golang formatting placeholders. For more information, please follow other related articles on the PHP Chinese website!