What is the difference between if(CONST==variable) or if(variable==CONST)?

Question

Is there a difference in the order of the comparison operator?

#define CONST_VALUE 5

int variable;

...

if ( variable == CONST_VALUE )   // Method 1
...

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Answer 1

The only difference is that ( CONST_VALUE == variable ) makes the common typo ( CONST_VALUE = variable ) impossible to compile.

By comparison, if ( variable = CONST_VALUE ) will result in the compiler thinking you meant to assign CONST_VALUE to 'variable'.

The =/== confusion is a pretty common source of bugs in C, which is why people are trying to work around the issue with coding conventions.

Of course, this won't save you if you're comparing two variables.

And the question seems to be a duplicate of How to check for equals? (0 == i) or (i == 0)

And here's some more information: http://cwe.mitre.org/data/definitions/481.html