什么是最简单的方法来填充左侧的0的字符串? [英] What is the easiest way to pad a string with 0 to the left?

问题描述

最简单的方法是在左侧填充0的字符串，这样

What is the easiest way to pad a string with 0 to the left so that

• "110" ="00000110"

• "110" = "00000110"

"11110000" ="11110000"

"11110000" = "11110000"

我尝试使用format!宏，但它仅向右填充空格:

I have tried to use the format! macro but it only pads to the right with space:

format!("{:08}", string);

推荐答案

fmt模块文档描述了所有格式选项:

The fmt module documentation describes all the formatting options:

填充/对齐

通常将填充字符与 width参数.这表示如果要格式化的值是 小于width的地方，将会在其周围打印一些额外的字符. 多余的字符由fill指定，对齐方式可以是 以下选项之一:

Fill / Alignment

The fill character is provided normally in conjunction with the width parameter. This indicates that if the value being formatted is smaller than width some extra characters will be printed around it. The extra characters are specified by fill, and the alignment can be one of the following options:

• <-参数在width列中左对齐
• ^-参数在width列中居中对齐
• >-参数在width列中右对齐

• < - the argument is left-aligned in width columns
• ^ - the argument is center-aligned in width columns
• > - the argument is right-aligned in width columns

---

assert_eq!("00000110", format!("{:0>8}", "110"));
//                                |||
//                                ||+-- width
//                                |+--- align
//                                +---- fill

另请参阅:

• 使用std :: fmt格式化时，如何以可变数量对数字进行0填充?
• 如何打印带有前导零的二进制整数?
• 带有填充零的十六进制格式
• 在Rust中将二进制字符串转换为带有前导零的十六进制字符串

• How can I 0-pad a number by a variable amount when formatting with std::fmt?
• How do I print an integer in binary with leading zeros?
• Hexadecimal formating with padded zeroes
• Convert binary string to hex string with leading zeroes in Rust

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