Virtual Gate Test Series: Programming & DS - Parameter Passing

Question

int f(int &x, int c)
   {
    c = c-1;
    if (c == 0) return 1;
        x = x +1;
    return f(x,c) * x;
   }

 

What is the return value of $f(p,p),$ if the value of $p$ is initialized to $4$ before the call$?$ Note that the first parameter is passed by

reference, whereas the second parameter is passed by value.

Comments

343????

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yes... explain

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the function u are calling is one argument is passing the address of variable and second argument is simply a value, so the receiving function must have the first argument as a pointer so that it can take the address of a variable, the second argument is only value.

so simple just replace x with "*x" and then execute code u will get 343.

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It's undefined behavior, check my answer.

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yes, in that 2013 qstn, marks were given to all as the code produces undefined behavior.

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In GATE such question comes again

do u leave it unanswered ?

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@srestha

If by mistake again Undefined behavior type question again come in GATE, and if you understand in exam hall that this question produce Undefined behavior then attempt that question .. generally marks given to all , in worst case if not given then you can challenge atleast if you attempt.

Answer 1

This is same as to GATE 2013 questions except there initial value is 5.

Answer is undefined behaviour due to sequence point. 

Refer this answer by arjun sir : https://gateoverflow.in/60/gate2013-42