Functions Questions and Answers

Q: What is the output of this C code? int x = 5; void main() { int x = 3; printf("%d", x); { int x = 4; } printf("%d", x); }

Correct answer: 3 3Here the inner int x = 4; is a declaration, so it creates a new variable that shadows the outer one for the length of the block and then disappears. main’s own x is untouched, and both printf calls show 3.

Q: Functions in C are ALWAYS:

Correct answer: ExternalA function in C has external linkage by default: its name is visible to every other file linked with it. That is why two files cannot define functions of the same name, and why static is used to confine a function to its own file.

Q: What is the default return type if it is not specified in function definition?

Correct answer: intUnder the older rules an omitted return type defaults to int. C99 removed the implicit int, so a modern compiler warns or refuses - but the default, where it is honoured, is int.

Q: Property of external variable to be accessed by any source file is called by C90 standard as:

Correct answer: external linkageLinkage is the term for whether a name refers to the same object across translation units; scope is where a name is visible within one. A file-scope variable has external linkage - the same object however many files declare it.

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

Correct answer: Infinite him calls itself as its last action, with no condition to stop it - unbounded recursion. It prints hi each time, so the output repeats until the stack is exhausted and the program crashes.

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

Correct answer: Data segmentp is a file-scope variable with an explicit initialiser, so it goes in the data segment, which holds initialised statics and whose contents come from the executable file. (Strictly, a pointer initialised to NULL is all-zero and many toolchains put it in BSS after all; the distinction the question is drawing is between explicitly initialised and not.)

Q: What is the output of this C code? int x; void main() { printf("%d", x); }

Correct answer: 0A variable at file scope has static storage duration, and every such object is zero-initialised before the program starts - it is not left holding junk, as an uninitialised automatic variable would be. So the value printed is 0.

Q: Which of the following is an external variable? int func (int a) { int b; return b; } int main() { int c; func (c); } int d;

Correct answer: dd is declared at file scope, so it is the external variable - even though it appears at the end of the file, which merely limits how much of the file can see it. a is a parameter, and b and c are locals; all three are automatic.

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

Correct answer: Compile time errorm is defined inside main, which standard C forbids - and it is also called before its definition is reached. The compiler rejects the program.

101.

What is the output of this C code?

int x = 5;
    void main()
    {
        int x = 3;
        printf("%d", x);
        {
            int x = 4;
        }
        printf("%d", x);
    }

A.3 3
B.3 4
C.3 5
D.Run time error

Answer: A

Correct answer: 3 3

Here the inner int x = 4; is a declaration, so it creates a new variable that shadows the outer one for the length of the block and then disappears. main’s own x is untouched, and both printf calls show 3.

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102.

What will happen after compiling and running following code?

main()
{
  printf("%p", main);
}

A.Error
B.Will make an infinite loop.
C.Some address will be printed.
D.None of these.

Answer: C

Function names are just addresses (just like array names are addresses).
main() is also a function. So the address of function main will be printed. %p in printf specifies that the argument is an address. They will be printed as hexadecimal numbers.

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103.

Functions in C are ALWAYS:

A.Internal
B.External
C.Both Internal and External
D.External and Internal are not valid terms for functions

Answer: B

Correct answer: External

A function in C has external linkage by default: its name is visible to every other file linked with it. That is why two files cannot define functions of the same name, and why static is used to confine a function to its own file.

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104.

What is the default return type if it is not specified in function definition?

A.void
B.int
C.double
D.short int

Answer: B

Correct answer: int

Under the older rules an omitted return type defaults to int. C99 removed the implicit int, so a modern compiler warns or refuses - but the default, where it is honoured, is int.

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105.

Property of external variable to be accessed by any source file is called by C90 standard as:

A.external linkage
B.external scope
C.global scope
D.global linkage

Answer: A

Correct answer: external linkage

Linkage is the term for whether a name refers to the same object across translation units; scope is where a name is visible within one. A file-scope variable has external linkage - the same object however many files declare it.

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106.

What is the output of this C code?

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

A.Compile time error
B.hi
C.Infinite hi
D.Nothing

Answer: C

Correct answer: Infinite hi

m calls itself as its last action, with no condition to stop it - unbounded recursion. It prints hi each time, so the output repeats until the stack is exhausted and the program crashes.

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107.

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

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

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

Answer: B

Correct answer: Data segment

p is a file-scope variable with an explicit initialiser, so it goes in the data segment, which holds initialised statics and whose contents come from the executable file. (Strictly, a pointer initialised to NULL is all-zero and many toolchains put it in BSS after all; the distinction the question is drawing is between explicitly initialised and not.)

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108.

What is the output of this C code?

int x;
    void main()
    {
        printf("%d", x);
    }

A.Junk value
B.Run time error
C.Undefined
D.0

Answer: D

Correct answer: 0

A variable at file scope has static storage duration, and every such object is zero-initialised before the program starts - it is not left holding junk, as an uninitialised automatic variable would be. So the value printed is 0.

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109.

Which of the following is an external variable?

int func (int a)
    {
        int b;
        return b;
    }
    int main()
    {
        int c;
        func (c);
    }
    int d;

Answer: D

Correct answer: d

d is declared at file scope, so it is the external variable - even though it appears at the end of the file, which merely limits how much of the file can see it. a is a parameter, and b and c are locals; all three are automatic.

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110.

What is the output of this C code?

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

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

Answer: B

Correct answer: Compile time error

m is defined inside main, which standard C forbids - and it is also called before its definition is reached. The compiler rejects the program.

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