php - Regex to add a comma after every sequence of digits in a string -

i want regex or loop on numbers in string , add comma after them. if there comma shouldn't it.

example:

$string="21 beverly hills 90010, ca"; 

output:

$string="21, beverly hills 90010, ca"; 

thanks

you do

$string = preg_replace('/(?<=\d\b)(?!,)/', ',', $string); 

explanation:

(?<=\d\b) # assert current position right of digit           # , digit last 1 in number            # (\b = word boundary anchor). (?!,)     # assert there no comma right of current position 

then insert comma in position. done.

this not insert comma between number , letter (it not change 21a broadway 21,a broadway) because \b matches between alphanumeric , non-alphanumeric characters. if want this, use /(?<=\d)(?![\d,])/ instead.