Question

I have been trying some programs in the C Language and come across to this…

#include<stdio.h>
int main()
{
    int j = 3, k;
    k= !5 && j;
    printf("%d", k);
    return 0;
}

Can anyone figure out what is the problem in this if I compile the program I will result to 0.

and when I tried the same code in C#

public void logic()
{
    j = 5;
    k = !4 && j;
    Console.WriteLine("hence the value would be " + k);
}

this will generate the error

( Error 1 Operator ‘!’ cannot be applied to operand of type ‘int’ C:\Documents and Settings\SANDEEP\My Documents\Visual Studio 2005\Projects\ConsoleApplication18\ConsoleApplication18\Program.cs 21 17 ConsoleApplication18 )

I want to know why the output of my C code is not working, and how can I use the ! operator in C#.
Please help.

Answer 1

In C, any non-zero value such as 5 is considered to be “true”, therefore !5 evaluates to 0, or “false”. Thus, 0 && 3 is false as well. Logical operators in C.

In C#, the type system is a little stronger in this respect. The ! operator only works on values of type bool, which is completely independent of the integer types. See ! Operator in C#.