What is the default return type of a function in C if not specified?
In older C standards (before C99), if no return type is specified, the default is 'int'. However, this is deprecated in modern C standards.
What is the difference between function declaration and function definition?
Declaration (prototype) tells the compiler about the function signature; definition provides the actual function body and implementation.
What happens if a function does not have a return statement?
If a function with a non-void return type lacks a return statement, it returns undefined/garbage value. For void functions, no return is needed.
Which of the following function calls is valid?
int calculate(int a, float b, char c);
All three parameters must be provided in correct order and compatible types.
What is a recursive function?
A recursive function is one that calls itself. It must have a base case to avoid infinite recursion.
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What is the issue with the following code?
int factorial(int n) { return n * factorial(n-1); }
The recursive function lacks a base case (like if n==0 return 1) to terminate recursion, causing infinite recursion and stack overflow.
In C, are function parameters passed by value or by reference by default?
C passes parameters by value by default. To achieve pass-by-reference effect, pointers must be used explicitly.
What will be the output?
void modify(int x) { x = x + 10; }
int main() { int a = 5; modify(a); printf("%d", a); }
Since parameters are passed by value, changes to 'x' inside modify() don't affect 'a' in main(). Output is 5.
Which of the following correctly declares a function pointer that points to a function returning int and taking two int parameters?
The correct syntax for function pointer is return_type (*pointer_name)(parameter_types). Option A is correct.
In C, when a function is called with fewer arguments than declared, what happens?
Old-style K&R C declarations don't perform argument checking, allowing calls with fewer arguments. Modern prototyped functions generate compiler errors.
What will be printed by this code?
void func(int arr[10]) { printf("%lu", sizeof(arr)); }
int main() { int a[10]; func(a); }
When arrays are passed to functions, they decay to pointers. sizeof(arr) returns the size of the pointer, not the array.
What is the correct way to declare a function that accepts variable number of arguments?
Variadic functions require at least one named parameter before the ellipsis. Both options B and C follow the correct syntax.
Which of the following is true about a static function in C?
A static function has file scope and cannot be accessed from other translation units, providing encapsulation.
What happens if a function declared as returning int doesn't contain a return statement?
Without an explicit return statement, the function returns whatever value is in the return register, which is undefined behavior.
Which of the following correctly represents a callback function scenario?
A callback function is a function pointer passed to another function, which calls it at a later point in time.
Which of the following about function declaration and definition is TRUE?
Functions can have multiple forward declarations but only one definition. This allows function prototypes in header files.
What will happen when this code executes?
void func() { func(); } int main() { func(); }
This is infinite recursion with no base case, causing stack overflow as the function keeps calling itself.
Which of the following is a valid function pointer initialization?
Both forms are valid. Functions decay to function pointers, so both &printf and printf assign the function address correctly.
Consider the code: int calculate(int a, int b = 5) { return a + b; }. What is the issue?
Default parameters are a C++ feature, not available in standard C. C requires explicit arguments for all parameters.
What will be the output of this recursive function? int fact(int n) { if(n <= 1) return 1; return n * fact(n-1); } fact(5)
This calculates factorial. fact(5) = 5*4*3*2*1 = 120. Base case n<=1 stops recursion.
