Conditional OR statement

Just wondering what the syntax would be for a multiple conditional OR statement when comparing strlen to various lengths from a header file.

Just wondering if this is correct.
if( strlen( a ) != b || c || d )
{
…
}

Let me know if I’ve misunderstood or missed and parentheses I might have needed.

>Solution :

This will give you the correct answer, but it won’t work the way you think it will.

Conditions are evaluated individually. This means that for the following code :

char* a = "test";
int b = 2;
int c = 3;
int d = 4;
if(strlen(a) != b || c || d )
{
   …
}

… will do the following :

if((4 != 2) || (3) || (4))

Since positive integers are evaluated as true :

if((true) || (true) || (true))

Which evaluates as true.

What you really want there is the following :

if((strlen(a) != b) || (strlen(a) != c) || (strlen(a) != d))
{
   …
}

Or, for a better optimized version :

int len = strlen(a);
if((len != b) || (len != c) || (len != d))
{
   …
}

EDIT :

As it was pointed out in the comments, what you really want to validate here is if a string length isn’t one of three things. So what you need is the AND operator.

int len = strlen(a);
if((len != b) && (len != c) && (len != d))
{
   …
}