Thread: Not getting the desired o/p with ~ operator. Kindly help.

  1. 05-24-2011 #1
    DevinLgls
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    Question Not getting the desired o/p with ~ operator. Kindly help.

    Hi everybody, I was wondering if you could help me with this ~ operator.

    I just tried the following simple program in my Turbo C;

    Code:
    int main() {

unsigned short int i = ~0;
printf("%d", i);

return 0;
}
    i expected the program to return the maximum value that can be stored i.e: 65535 but the o/p produced was -1. Also, when i tried the same program in codepad.org (online compiler), the o/p was 65535. And in both my PC and the online version the ~ doesn't seem to be producing the expected o/p for other integer types such as "int", "long" etc.

    Can you someone please tell me if i'm doing anything wrong? Thanks
  2. 05-24-2011 #2
    Salem
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    Well on your fossilised TurboC, short int and int are the same size, so the MSB of ~0 is also the sign bit - you get -1

    On some other machine, short int is 16 bits, (0x0000 or 0xFFFF) and an int is 32-bits.
    So it can comfortably hold the promoted unsigned value of 65535 and that is what you see.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
  3. 05-24-2011 #3
    DevinLgls
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    @Salem Thanks for the clarification. can you recommend a good compiler to run on my Win7? I'm returning to C programming after many years so trying to catchup
  4. 05-24-2011 #4
    CommonTater
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    Quote Originally Posted by DevinLgls View Post
    @Salem Thanks for the clarification. can you recommend a good compiler to run on my Win7? I'm returning to C programming after many years so trying to catchup
    Free C / C++ Compilers and Interpreters (thefreecountry.com)
  5. 05-24-2011 #5
    Salem
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    Most people seem to go for one (or more) of these.
    Microsoft Express Downloads - Visual Studio Express and SQL Server Express

    smorgasbordet - Pelles C

    Code::Blocks
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
  6. 05-24-2011 #6
    DevinLgls
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    Thumbs up

    Salem & CommonTater. Thanks a lot for your suggestions. this forum rocks!
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