ISRO2018-1

Question

Consider the following program

{
    int x=1;
    printf("%d",(*char(char*)&x));
}

Assuming required header files are included and if the machine in which this program is executed is little endian, then the output will be

• A. 0
• B. 99999999
• C. 1
• D. unpredictable

Comments

A. 0

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I think, it should be either "no output"(gcc) or "error"(zapcc) depending on the type of compiler used. The problem is with "*char" part because we don't need to typecast it again to access the value stored at the type-casted char pointer. Thus, option D should be the answer.

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unpredictable means undefined behavior?

It is working on certain value 1, then why will be undefined behavior?

Moreover it is working on little endian machine

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It gives the below error:

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Here integer typecasting to  char pointer

Without last pointer code will work

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In that case, the answer would be 1. But since they have used *char, it won't work. We don't need to typecast it(again) to get the value stored at the char pointer.

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which year of ISRO paper is this?

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22 april 2018

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https://www.geeksforgeeks.org/little-and-big-endian-mystery/

useful to understand Big endian and little endian.

Answer 1

main()
{
int x=1;
printf("%d",(*char(char*)&x));
}

Here,we will get a compilation error because 'char' is extra.

If the code is :

main()
{
int x=1;
printf("%d",(*(char*)&x));
}

 

OUTPUT: 1 option(c)

Comments

I too marked it (c) i.e. 1

But due to compilation error in the actual code, none of the options is correct.

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What is answer in ISRO key

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Given the option then I feel Option $\mathbf{(d)}$ is safe to mark.

Answer 2

Little endian is given, so A

Comments

What will be the output if Big Endian was given?

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if its big endian the number 1 can be represented as 00000001 00000000 00000000 00000000 if int occupies four bytes hence the answer will be 1.