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Editorial Team
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Asked: 2026-06-15T17:45:25+00:00

I’ve gotten bitten more than once by a bug where you accidentally assign a

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I’ve gotten bitten more than once by a bug where you accidentally assign a variable inside a conditional statement, like if.

I’m looking to grep my sources for such occurances. I created an expression that works in PHP for the simple case, but was wondering if anyone could optimize it or handle the more interesting cases.

Samples:

if ($var = 3)       //MATCH
if($var = 3)        //MATCH
if($var=3)          //MATCH
if ( $var = 3)      //MATCH
if ($var == $var2)  
if ($var = $var3)   //MATCH
if ( $var === 7)
if( $var == 8 || $var = 9) //MATCH
if (($var == 7 ) && ($var ==10))

The simple cases are handled well by if\s*\([\$a-zA-Z\d\s]*=[\$a-zA-Z\d\s]*\) but it would be nice to come up with something that works for the extended versions at the bottom of the sample.

Any ideas on better expressions?

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1 Answer

  1. Editorial Team

    First, let’s assume you don’t have cases like this (C example):

    if ((a = b) == c)

    because understanding these cases needs an actual parser.

    Now, simply put, you want to match = but not ==\+. Therefore:

    if\([^=]\|==\+\)*[^=]=[^=]\([^=]\|==\+\)*$

    What it says:

    • if: match the first if.
    • [^=]: any character but =
    • ==\+: == and ===
    • \([^=]\|==\+\)*: anything that is not = or is == or ===. This includes all the whitespace, the beginning (, ending ) etc. This comes both before and after the isolated =.
    • [^=]=[^=]: isolated =.
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