Str_pad (string, length, padding string, padding type)
parameter
String // required. Specifies the string to fill.
Length//required. Specify a new string length. If the value is less than the original length of the string, nothing is done.
Pad_string // optional. Specifies the string used for padding. The default value is empty.
Pad_type // optional. Specifies which side of the string to fill.
Please refer to: /article/8395.html for detailed usage.