How to format numbers with 00 prefixes in php?

Question

I'm trying to generate invoice numbers. They should always be 4 numbers long, with leading zeros, for example :

• 1 -> Invoice 0001
• 10 -> Invoice 0010
• 150 -> Invoice 0150

etc.

Answer 1

Use str_pad().

$invID = str_pad($invID, 4, '0', STR_PAD_LEFT);