CODEWITHSUNDEEP
visual-c++
silver surfer
silver surfer

Reputation: 258

Equality operator while checking condition in C++

IS there a difference between these two conditions:

if (a==5) and if (5==a)?

Upvotes: 1

Views: 90

Answers (3)

David Buck
David Buck

Reputation: 2847

If 'a' points to an object that overrides ==, then you may get different results in theory.

Upvotes: 1

Jerry Coffin
Jerry Coffin

Reputation: 490048

The two are normally the same.

Some people recommend putting the constant first (if (5==a)) because this way, if you mis-type and leave out one of the = to get: if (5=a), the compiler will give an error message, whereas if (a=5) will compile and execute, but probably not do what you want.

Some compilers will give a warning for the latter (e.g., recent iterations of gnu do) but others don't (and Visual C++ is among the latter).

Upvotes: 1

Pablo Santa Cruz
Pablo Santa Cruz

Reputation: 181270

No, there is no difference at all.

People used to write this expression 5==a instead of a==5 so the could catch a=5 errors on C/C++ where that expression is perfectly valid and always evaluates to true. That way, if programmer writes (by mistake) the expression 5=a then it will get a compiler error.

Upvotes: 1

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