PHP prepend前导零，在单个数字前，即时。

PHP - Is there a quick, on-the-fly method to test for a single character string, then prepend a leading zero?

PHP -是否有一个快速的方法来测试单个字符串，然后在前置式0之前进行测试?

Example:

例子:

$year = 11;
$month = 4;

$stamp = $year.add_single_zero_if_needed($month);  // Imaginary function

echo $stamp; // 1104

4 个解决方案

#1

359

You can use sprintf: http://php.net/manual/en/function.sprintf.php

您可以使用sprintf: http://php.net/manual/en/function.sprintf.php

<?php
$num = 4;
$num_padded = sprintf("%02d", $num);
echo $num_padded; // returns 04
?>

It will only add the zero if it's less than the required number of characters.

它只会在小于所需字符数时添加零。

Edit: As pointed out by @FelipeAls:

编辑:如@FelipeAls所指出:

When working with numbers, you should use %d (rather than %s), especially when there is the potential for negative numbers. If you're only using positive numbers, either option works fine.

当处理数字时，应该使用%d(而不是%s)，特别是当可能出现负数时。如果你只使用正数，任何一种都可以。

For example:

例如:

sprintf("%04s", 10); returns 0010
sprintf("%04s", -10); returns 0-10

sprintf(“% 04年代”,10);0010年返回sprintf(“% 04年代”,-10);返回清廉

Where as:

的地方:

sprintf("%04d", 10); returns 0010
sprintf("%04d", -10); returns -010

sprintf(“% 04 d”,10);0010年返回sprintf(“% 04 d ",-10);返回-010

#2

150

You can use str_pad for adding 0's

可以使用str_pad添加0

str_pad($month, 2, '0', STR_PAD_LEFT);

string str_pad ( string $input , int $pad_length [, string $pad_string = " " [, int $pad_type = STR_PAD_RIGHT ]] )

字符串str_pad (string $input, int $pad_length [， string $pad_string = " " [， int $pad_type = STR_PAD_RIGHT]])

#3

The universal tool for string formatting, sprintf:

字符串格式通用工具，sprintf:

$stamp = sprintf('%s%02s', $year, $month);

http://php.net/manual/en/function.sprintf.php

#4

It looks like they take a lot of lines to make it work. I use this short IF functionality and it gives the same result as OP wants.

看起来他们需要很多线才能让它工作。我使用这个简短的IF功能，它提供的结果与OP想要的一样。

$month = 8;
echo ($month < 10 ? '0'.$month : $month); // output: 08

And it takes only 1 line to show the correct output

只需要一行就能显示出正确的输出

#1

359