Test: Functions in C - Computer Science Engineering (CSE) MCQ

In C, functions are global by default. Unlike global functions, access to static functions is restricted to the file where they are declared. We can have file level encapsulation using static variables/functions in C because when we make a global variable static, access to the variable becomes limited to the file in which it is declared.

This is a simple program with function pointers. fun is assigned to point to demo. So the two statements "(*fun)();" and "fun();" mean the same thing.

The only problem with program is fun is not declared/defined before it is assigned to ptr. The following program works fine and prints "EduRevQuiz EduRevQuiz EduRevQuiz "

int fun(int n);

int main()
{
    // ptr is a pointer to function fun()
    int (*ptr)(int ) = fun;

    // fun() called using pointer 
    (*ptr)(3);
    return 0;
}

int fun(int n)
{
  for(;n > 0; n--)
    printf("EduRevQuiz ");
}

In C, functions can return any type except arrays and functions. We can get around this limitation by returning pointer to array or pointer to function.

Name of the function is actually a pointer variable to the function and prints the address of the function. Symbol table is implemented like this.

struct
{
   char *name;
   int (*funcptr)();
}
symtab[] = {
   "func", func,
   "anotherfunc", anotherfunc,
};

When parameters are passed to a function, the value of every parameter is evaluated before being passed to the function. What is the order of evaluation of parameters - left-to-right or right-to-left? If evaluation order is left-to-right, then output should be 5 6 7 and if the evaluation order is right-to-left, then output should be 7 6 5. Unfortunately, there is no fixed order defined by C standard. A compiler may choose to evaluate either from left-to-right. So the output is compiler dependent.

Empty list in C mean that the parameter list is not specified and function can be called with any parameters. In C, to declare a function that can only be called without any parameter, we should use "void fun(void)" As a side note, in C++, empty list means function can only be called without any parameter. In C++, both void fun() and void fun(void) are same.

extern keyword is used for global variables. Functions are global anyways, so adding extern doesn't add anything.

In c three continuous dots is known as ellipsis which is variable number of arguments of function. The values to parameters are assigned one by one. Now the question is how to access other arguments. See this for details.

Answer:(A) Explanation:In C, function parameters are always passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values.