Why use !! when converting int to bool?

Question

What can be a reason for converting an integer to a boolean in this way?

bool booleanValue = !!integerValue;

instead of just

Answer 1

Another option is the ternary operator which appears to generate one line less of assembly code (in Visual Studio 2005 anyways):

bool ternary_test = ( int_val == 0 ) ? false : true;

which produces the assembly code:

cmp DWORD PTR _int_val$[ebp], 0
setne   al
mov BYTE PTR _ternary_test$[ebp], al

Versus:

bool not_equal_test = ( int_val != 0 );

which produces:

xor eax, eax
cmp DWORD PTR _int_val$[ebp], 0
setne   al
mov BYTE PTR _not_equal_test$[ebp], al

I know it isn't a huge difference but I was curious about it and just thought that I would share my findings.