Regex Number followed by symbol issue

Why is the 3rd term not -6_?

$lefteq="-x+2+10x-9-6_";
$lct = preg_match_all('/(\-)?(\d+)(\-|\+|\=|\>|\<|\_)/', $lefteq, $match, PREG_PATTERN_ORDER);
for ($x=0;$x<$lct;$x++){
$curvalue=$match[0][$x];
echo "curvalue = " . $curvalue . "<br />";
$curvalue=substr($curvalue,0,strlen($curvalue)-1);
array_push($lconst,$curvalue);
}
which produces

curvalue = 2+
curvalue = -9-
curvalue = 6_

$lct = preg_match_all('/(\-)?(\d+?)(\-|\+|\=|\>|\<|\_)/', $lefteq, $match, PREG_PATTERN_ORDER);


or:


$lct = preg_match_all('/(\-)?(\d+)(\-|\+|\=|\>|\<|\_)/u', $lefteq, $match, PREG_PATTERN_ORDER);


or:


$lct = preg_match_all('/^(\-)?(\d+)(\-|\+|\=|\>|\<|\_)/', $lefteq, $match, PREG_PATTERN_ORDER);


should do as you expect.

2 of them did the same as what I had, and the one with the line starter ^ showed nothing.

What is it supposed to match? All or part of the string? If partial, which part? Btw, do a search on Google or such for 'PCRE cheat sheet'. It'll help with the specifics of regex.

It is supposed to match any number, positive or negative, followed by an operator sign or an underscore.

The only trouble I have in unit testing is that a negative number followed by a negative number comes up as negative positive. Everything else works like a charm.

I'll check the cheatsheet out.

Tried this instead, I removed the underscore from the end of $lefteq:
I'm looking for any number not followed by a letter. This gives the last negative number, but also gives the 1 in the number 10.

$lct = preg_match_all('/(\-?)(\d+)(?![a-z])/', $lefteq, $match, PREG_PATTERN_ORDER);

Fixed. I needed boundaries on the number. This solves my problem:

$lct = preg_match_all('/(\-?)\b(\d+)\b(?![a-z])/', $lefteq, $match, PREG_PATTERN_ORDER);

I'm looking for any number not followed by a letter.

I'm a bit rusty, but try this:


preg_match_all('/(\d+)(?![a-z])/', $lefteq, $match, PREG_PATTERN_ORDER);


Try looking in $match[1] instead of $match[0] too.


Edit: You shouldn't need to use the boundary marker.