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Is there any difference between writing

int i = 10;
if(i==10)
{
}

or 

if(10==i)
{
}

I read somewhere that in one way compiling is faster.

Thanks in advance.

Posted 16-Dec-10 21:25pm

ShilpiP

Updated 16-Dec-10 21:29pm

JF2015

v2

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3 solutions

Solution 1

There should be no difference. The only thing that is handy if you always use:

if(10==i)

might be, that it will give you a compile time error when you mistakingly write:

if(10=i)

Posted 16-Dec-10 21:28pm

JF2015

Solution 3

If the types are identical it will not make a difference (between 10==i and i==10) since the same operator== will be called and the optimizer should chose the most efficient comparison. The only question is whether your compiler treats the constant 10 as a int, long, size_t, etc...

As far as

if (int i==10) {
}

versus
int i=10;
if (10==i) {
}

The former should be preferred.

Posted 18-Dec-10 21:36pm

T2102

Updated 18-Dec-10 22:52pm

v2

Comments

Abhinav S 19-Dec-10 4:52am

Added code tags.

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User 7429338 · Accepted Answer · 2010-12-16T21:31:00

Solution 2

There is no functional difference, both will give the same comparison result.

As for compiling speed, that would depend on the way the compiler was coded. Modern compilers are generally smart enough to recognise the statements are functionally identical and treat them the same.

Posted 16-Dec-10 21:31pm

User 7429338

Comments

ShilpiP 17-Dec-10 3:39am

What if compiler are not modern than which statement execute faster??

[no name] 17-Dec-10 3:44am

If the compiler doesn't recognise the statements as functionally identical and compiling speed is different, it depends on the implementation of the compiler. There is no general answer to say which is faster.

Dalek Dave 17-Dec-10 3:56am

Good answer.

Abhinav S 19-Dec-10 4:52am

Good answer.