You can use chunk_split [docs]:
$str = chunk_split($rows['value'], 4, ' ');
DEMO
If the length of the string is a multiple of four but you don’t want a trailing space, you can pass the result to trim.
You can use chunk_split [docs]:
$str = chunk_split($rows['value'], 4, ' ');
DEMO
If the length of the string is a multiple of four but you don’t want a trailing space, you can pass the result to trim.