What will be the output?
int main()
{
printf("%d", d++);
}
int d = 10;
Answer: D
Correct answer: Compile time error
d is declared after main, so at the point of use it is not in scope. Under C99 and later an undeclared identifier is an error; older compilers would have assumed int and then found the later definition consistent, but the modern answer is a compile error.
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The keyword used to transfer control from a function back to the calling function is
Answer: D
The keyword return is used to transfer control from a function back to the calling function.
Example:
#include
int add(int, int); /* Function prototype */
int main()
{
int a = 4, b = 3, c;
c = add(a, b);
printf("c = %d\n", c);
return 0;
}
int add(int a, int b)
{
/* returns the value and control back to main() function */
return (a+b);
}
Output: c = 7
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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);
}
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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What will happen after compiling and running following code?
main()
{
printf("%p", main);
}
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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Functions in C are ALWAYS:
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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What is the default return type if it is not specified in function definition?
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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Property of external variable to be accessed by any source file is called by C90 standard as:
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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What is the output of this C code?
void main()
{
m();
}
void m()
{
printf("hi");
m();
}
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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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;
}
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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What is the output of this C code?
int x;
void main()
{
printf("%d", x);
}
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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