Functions Questions and Answers

Q: What is the problem in the following declarations? int func(int); double func(int); int func(float);

Correct answer: All of the mentionedC has no function overloading: one name may denote only one function in a translation unit. So none of the three variations is allowed - not a different signature, not a different return type, not a different number of parameters. (C++ permits overloading on the parameters, though still not on the return type alone.)

Q: Array sizes are optional during array declaration by using ______ keyword.

Correct answer: externAn extern declaration says the array is defined elsewhere, so its size may be omitted: extern int a[];. The definition in the other file supplies the size. Note the consequence - sizeof cannot be applied to it in this file, since the compiler does not know how big it is.

Q: Which of the following cannot be static in C?

Correct answer: None of the mentionedVariables and functions can both be static, which gives them internal linkage or, for a local variable, a lifetime as long as the program’s. A structure variable can be static too. What cannot be static is a structure type - but a type has no storage class in the first place.

Q: In C all functions except main() can be called recursively.

Correct answer: Falsemain can be called recursively in C - it is an ordinary function in that respect, and the standard permits it. (C++ forbids it.) So the statement that every function except main may recurse is false.

Q: What is the output of this C code? void m() { printf("hi"); } void main() { m(); }

Correct answer: him is defined before main, so it is already declared when the call is reached, and it simply prints hi. (void main() is non-standard, but every compiler accepts it.)

Q: What is the output of this C code? int main() { auto i = 10; const auto int *p = &i; printf("%d\n", i); }

Correct answer: 10auto i = 10; relies on the old implicit int, and const auto int *p combines a qualifier with a storage class, which is allowed. The program prints 10 - though a modern compiler will warn, since C99 removed implicit int.

Q: Which part of the program address space is p stored in the code given below? int *p; int main() { int i = 0; p = &i; return 0; }

Correct answer: Bss segmentp is at file scope with no initialiser, so it belongs in BSS - the block reserved for zero-initialised statics. BSS occupies no space in the executable file: only its size is recorded, and the loader zeroes it, which is why an uninitialised global costs nothing on disk.

Q: Every function must return a value

Correct answer: NoA function declared void returns nothing at all, and needs no return statement - reaching the closing brace ends it. Only a function with a non-void return type is obliged to return a value.

Q: Can variable i be accessed by functions in another source file? int i; int main() { printf("%d\n", i); }

Correct answer: trueA variable at file scope has external linkage by default, so another source file can reach it by declaring extern int i;. Adding static to the definition is what would prevent that.

Q: If return type for a function is not specified, it defaults to int

Correct answer: TrueUnder the older rules an omitted return type defaulted to int - which is why so much old code writes main() rather than int main(). C99 removed the default, so a modern compiler will at least warn.

31.

What is the problem in the following declarations?
     int func(int);
     double func(int);
     int func(float);

A.A function with same name cannot have different signatures
B.A function with same name cannot have different return types
C.A function with same name cannot have different number of parameters
D.All of the mentioned

Answer: D

Correct answer: All of the mentioned

C has no function overloading: one name may denote only one function in a translation unit. So none of the three variations is allowed - not a different signature, not a different return type, not a different number of parameters. (C++ permits overloading on the parameters, though still not on the return type alone.)

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32.

Array sizes are optional during array declaration by using ______ keyword.

A.auto
B.static
C.extern
D.register

Answer: C

Correct answer: extern

An extern declaration says the array is defined elsewhere, so its size may be omitted: extern int a[];. The definition in the other file supplies the size. Note the consequence - sizeof cannot be applied to it in this file, since the compiler does not know how big it is.

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33.

Which of the following cannot be static in C?

A.Variables
B.Functions
C.Structures
D.None of the mentioned

Answer: D

Correct answer: None of the mentioned

Variables and functions can both be static, which gives them internal linkage or, for a local variable, a lifetime as long as the program’s. A structure variable can be static too. What cannot be static is a structure type - but a type has no storage class in the first place.

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34.

In C all functions except main() can be called recursively.

A.True
B.False

Answer: B

Correct answer: False

main can be called recursively in C - it is an ordinary function in that respect, and the standard permits it. (C++ forbids it.) So the statement that every function except main may recurse is false.

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35.

What is the output of this C code?

void m()
{
printf("hi");
}
void main()
{
m();
}

A.hi
B.Run time error
C.Nothing
D.Varies

Answer: A

Correct answer: hi

m is defined before main, so it is already declared when the call is reached, and it simply prints hi. (void main() is non-standard, but every compiler accepts it.)

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36.

What is the output of this C code?

int main()
    {
        auto i = 10;
        const auto int *p = &i;
        printf("%d\n", i);
    }

A.10
B.Compile time error
C.Depends on the standard
D.Depends on the compiler

Answer: A

Correct answer: 10

auto i = 10; relies on the old implicit int, and const auto int *p combines a qualifier with a storage class, which is allowed. The program prints 10 - though a modern compiler will warn, since C99 removed implicit int.

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37.

Which part of the program address space is p stored in the code given below?

int *p;
    int main()
    {
        int i = 0;
        p = &i;
        return 0;
    }

A.Code/text segment
B.Data segment
C.Bss segment
D.Stack

Answer: C

Correct answer: Bss segment

p is at file scope with no initialiser, so it belongs in BSS - the block reserved for zero-initialised statics. BSS occupies no space in the executable file: only its size is recorded, and the loader zeroes it, which is why an uninitialised global costs nothing on disk.

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38.

Every function must return a value

A.Yes
B.No

Answer: B

Correct answer: No

A function declared void returns nothing at all, and needs no return statement - reaching the closing brace ends it. Only a function with a non-void return type is obliged to return a value.

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39.

Can variable i be accessed by functions in another source file?

int i;
    int main()
    {
        printf("%d\n", i);
    }

A.false
B.Only if static keyword is used
C.Depends on the type of the variable
D.true

Answer: D

Correct answer: true

A variable at file scope has external linkage by default, so another source file can reach it by declaring extern int i;. Adding static to the definition is what would prevent that.

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40.

If return type for a function is not specified, it defaults to int

A.True
B.False

Answer: A

Correct answer: True

Under the older rules an omitted return type defaulted to int - which is why so much old code writes main() rather than int main(). C99 removed the default, so a modern compiler will at least warn.

Discuss in Forum

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