Replace only the first character of a string with str_replace?

Question

I'm trying to replace only the first character of a string, but it isn't working, it replaces all the "0" on the string, here's my code:

$mes2 = str_replace('0', '', $mes[0]);

I want to replace the first character only if its a 0, example:

07 becomes 7

I don't want to replace all the time, example:

11 becomes 1, i don't want it.

I also tried this way, but it didn't work the way i want, because it's replacing also the second character if it's 0, like 10 becomes 1.

$mes2 = preg_replace('/0/', '', $mes, 1);

Answer 1

OK, based on refinements to your question, what you probably want is ltrim.

$out = ltrim($in, "0");

This will strip all leading zeroes from $in. It won't remove zeroes from anywhere else, and it won't remove anything other than zeroes. Be careful; if you give it "000" you'll get back "" instead of "0".

You could use typecasting instead, as long as $in is always a number (or you want it to result in 0 if it isn't):

$out = (int) $in;

• 007 becomes 7
• 000 becomes 0
• 100 stays as 100
• 456 stays as 456
• 00a becomes 0
• 56a becomes 0
• ab4 becomes 0
• -007 becomes -7

...etc.

Now, in the unlikely event that you only want to replace the first 0, so for example "007" becomes "07", then your latest attempt mentioned in your question is almost there. You just need to add a "caret" character to make sure it only matches the start of the string:

$out = preg_replace('/^0/', '', $in);