Use PHP to add zeros to the front of a specified number

PHP adds zeros to the front of the number and 0 to the fixed number of digits

When designing a unique number, a fixed number of digits is required, for example, a fixed four-digit format is required:

For example:

YSZC After 0001, the following set of numbers, how to make it increase automatically?

1->0001
56->0056
288->0288
1992->1992

We can use the PHP built-in function str_pad () function to pad the string to the new length.

str_pad(string,length,pad_string,pad_type)
//参数    描述
string      //必需。规定要填充的字符串。
length      //必需。规定新的字符串长度。如果该值小于字符串的原始长度，则不进行任何操作。
pad_string  //可选。规定供填充使用的字符串。默认是空白。
pad_type    //可选。规定填充字符串的哪边。
            //可能的值：
            STR_PAD_BOTH - //填充字符串的两侧。如果不是偶数，则右侧获得额外的填充。
            STR_PAD_LEFT - //填充字符串的左侧。
            STR_PAD_RIGHT - //填充字符串的右侧。默认。

For example, I wrote a method to first determine whether there is data in the data table. If not, initialize 0001, otherwise call the auto-increment ID.

/**
 * @desc 协议编号
 * @author  磊丰
 * @Date  2021/12/1 16:23
 * @param $num
 * @return string
 */
public function inc_privacy_no($num)
{
    $start = "0001";
    $data = 表::find('id');    //这里是查询表里的一条最新的sql数据,自己写
    if(empty($data)){
        return $num.$start;
    }
    $data_no = str_pad(($data['id']+1),4,"0",STR_PAD_LEFT);
    return $num.$data_no;
}

Calling method

$this->inc_privacy_no("YSZC")

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