plz explain the output of the program.

This is a discussion on plz explain the output of the program. within the C++ Programming forums, part of the General Programming Boards category; Code: union a { int a; char ch[2]; }; int main() { union a u; u.ch[0]=3; u.ch[1]=2; printf("%d %d %d", ...

  1. #1
    Registered User
    Join Date
    Apr 2008
    Posts
    8

    plz explain the output of the program.

    Code:
    union a
    {
    
     int a;
    char ch[2];
    };
    int main()
    
    { 
    
    union a u;
    
     u.ch[0]=3;
     u.ch[1]=2;
    
    
     printf("%d %d %d", u.ch[0],u.ch[1].u.a);
    }
    and the o/p is


    3 2 515

    some body plz exlain how...

  2. #2
    Banned
    Join Date
    Nov 2007
    Posts
    678
    I think your output will be different each time unless you happen to have

    char - 1 byte
    int - 2 bytes

  3. #3
    C++まいる!Cをこわせ! Elysia's Avatar
    Join Date
    Oct 2007
    Posts
    22,548
    Indeed... I get the same result if I make it a short.
    Anyway, it's setting the individual bytes of the int so to speak.
    Byte 1 = 3
    Byte 2 = 2
    On high endian machines, that would make the short equal to 0x0203.
    Input that into a calculator and convert to decimal and you get 515.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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