decrement operator vs subtraction operator

Question

If I write a code like(in c)

    x=1;
    z=2;
    y=x---z;

will first two - be treated as post-decrement and later one as subtraction

or first - will be treated as subtraction and other two as pre-decrement

and what if I put a space to make it the other (because in c program doesn't change by white space)

Also more specific duplicate [here](http://stackoverflow.com/questions/13874179/can-you-have-a-triple-minus-signs-in-c-programming-what-does-it-mean). — Lundin, Nov 03 '15 at 10:26

score 6 · Accepted Answer · answered Nov 03 '15 at 10:25

6

As per the C11 standard, chapter §6.4 , lexical elements, _{(emphasis mine)}

If the input stream has been parsed into preprocessing tokens up to a given character, the next preprocessing token is the longest sequence of characters that could constitute a preprocessing token. [..]

So,

y=x---z;

is

y= (x--) - z;

This is also called as Maximal munch rule.

answered Nov 03 '15 at 10:25

Sourav Ghosh

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but I have always thought that white space has no meaning in c – Dhruva Mehrotra Nov 03 '15 at 10:33
@DhruvaMehrotra unless they are used as separator(s), just as here... – Sourav Ghosh Nov 03 '15 at 10:35

decrement operator vs subtraction operator

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