Numbers and Symbols

[iversonm]

Hey I am sure this is easy enough but I have made my attempts and failed so I come to the Gods of Regex!

I want to only allow numbers 0-9 and + - * / and ^

any advice would be appreciated

[Daniel0]

Right, so a number is -?[0-9]+. Either of the operators +, -, *, / and ^ require a number on both sides.

 

preg_match('#^-?[0-9]+(?:[-+*/^](?:\(-[0-9]+\)|[0-9]+))*$', $string);

 

So basically, you can do 1*2, but you can't do 1*-2 because it needs to be 1*(-2). I didn't test it very thoroughly, but I'm pretty sure it works. It can probably be optimized as well.

[iversonm]

No ending delimiter '#' found

i have no idea what that means

[Daniel0]

Sorry, make it

preg_match('#^-?[0-9]+(?:[-+*/^](?:\(-[0-9]+\)|[0-9]+))*$#', $string);

[iversonm]

assuming

preg_match('#^-?[0-9.]+(?:[-+*/^](?:\(-[0-9.]+\)|[0-9.]+))*$#', $string)

works for decimals then topic solved. you are my hero

[Daniel0]

Well, it will work for decimals, but it will also allow illegal things like this: 1.2.3.4.5.....7

 

You can do like this:

preg_match('#^-?[0-9]+(?:\.[0-9])*(?:[-+*/^](?:\(-[0-9]+(?:\.[0-9])*\)|[0-9]+(?:\.[0-9])*))*$#', $string);

 

(untested)

[iversonm]

So what would I need to add if I want to allow numbers after the decimal to be as long as i want

so 1.1 is valid but 1.11 is not