Function — Part 1 MCQs with Explanations

In C, the function abs() is defined in stdlib.h and is used to compute the absolute value of an integer . Passing a floating-point number like -7.5 to abs() is incorrect because abs() expects an int argument. To handle floating-point numbers , C provides a different function called fabs() , which is defined in math.h . Therefore, using abs(-7.5) results in a compile-time error or unexpected behavior because the argument type does not match the function's expected parameter. Option A and B are incorrect because abs() cannot legally process a float. Option C is incorrect because while 7 is the integer part, the input is still a float and would not be accepted by abs() . Hence, the correct answer is Option D: Error .

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.

Option A: Must contain at least one function. Explanation: In C programming, every valid program must contain at least one function, which is typically the main() function. This function serves as the starting point of execution for the program. Option B: Need not contain any function. Explanation: This option is incorrect because every C program requires at least one function, typically the main() function, to execute. Option C: Needs input data. Explanation: While many programs do require input data, this is not a requirement for the structure of a C program itself. Input data is dependent on the specific requirements of the program being developed. Option D: None of the above. Explanation: This option is incorrect because Option A is correct—every C program must contain at least one function. Conclusion: Option A: Must contain at least one function.

return ( i++ ) it will first return i and then increment. i.e. 10 will be returned.

In C programming, the default parameter passing mechanism is call by value . Call by value : In this mechanism, a copy of the actual parameter's value is passed to the function. The function operates on this copy, and changes made to the parameter within the function do not affect the original argument. Call by reference : This is not the default mechanism in C. It involves passing the address of the actual parameter, allowing the function to modify the original value. Call by value result : This mechanism is not used by default in C. It involves passing a copy of the actual parameter and then updating the original variable with the result after the function execution. None of these : This option is incorrect because call by value is indeed the default parameter passing mechanism in C. Thus, Option A: call by value is the correct answer.

Compiler Error : Type mismatch in redeclaration of function display As the function display() is not defined before use, compiler will assume the return type of the function which is int (default return type). But when compiler will see the actual definition of display() , mismatch occurs since the function display() is declared as void . Hence the error.

The arguments in a function call are pushed into the stack from left to right. The evaluation is by popping out from the stack. and the evaluation is from right to left, hence the result. See the picture below

When static storage class is given, it is initialized once. The change in the value of a static variable is retained even between the function calls. Main is also treated like any other ordinary function, which can be called recursively.

In this recursive function call the function will return to main caller when the value of x is 4. Hence the output.

Because for each function call an entry is created in stack frame( known as Active Record Instance), and are executed in LIFO manner.

According to the prototype, the return type of scanf( ) function is int, that is the number of successful read input values.

Code organization and reusability is the correct answer to “In C, what is a function primarily used for”. This question is standard in competitive examination syllabi for Function.

4 is the correct answer to “What is the result of the expression sqrt(16) in C, assuming proper inclusion of the math library”. This question is standard in competitive examination syllabi for Function.

func() is the correct answer to “What is the correct way to declare a function in C that takes no arguments and returns an integer”. This question is standard in competitive examination syllabi for Function.

To return a value from the function is the correct answer to “In C, what is the purpose of the 'return' statement in a function”. This question is standard in competitive examination syllabi for Function.

rand is the correct answer to “Which of the following is not a standard C library function for mathematical operations”. This question is standard in competitive examination syllabi for Function.

Reducing code redundancy and improving code organization is the correct answer to “What is the main advantage of using functions in C”. This question is standard in competitive examination syllabi for Function.

void is the correct answer to “What is a function's return type in C if it does not return any value”. This question is standard in competitive examination syllabi for Function.

A variable declared within a function is the correct answer to “In C, what is a function parameter”. This question is standard in competitive examination syllabi for Function.

Limited to the function where it is declared is the correct answer to “How is the scope of a local variable defined in C”. This question is standard in competitive examination syllabi for Function.

A function that calls itself is the correct answer to “What is a recursive function in C”. This question is standard in competitive examination syllabi for Function.

5 is the correct answer to “What is the result of the expression abs(-5) in C”. This question is standard in competitive examination syllabi for Function.

A block of code that specifies a function's behavior is the correct answer to “In C, what is a function definition”. This question is standard in competitive examination syllabi for Function.

To specify that the function is not defined in the current file is the correct answer to “What is the purpose of the 'extern' keyword when declaring a function in C”. This question is standard in competitive examination syllabi for Function.

To limit the function's visibility to the current source file is the correct answer to “What is the purpose of the 'static' keyword when used with a function in C”. This question is standard in competitive examination syllabi for Function.

It specifies that the function doesn't return a value is the correct answer to “In C, what is the purpose of the 'void' keyword as a function return type”. This question is standard in competitive examination syllabi for Function.

myFunction(5, 10) is the correct answer to “How do you call a function named myFunction with two arguments in C”. This question is standard in competitive examination syllabi for Function.

A declaration that specifies a function's name and parameters is the correct answer to “In C, what is a function's prototype”. This question is standard in competitive examination syllabi for Function.

5 is the correct answer to “What is the result of the expression floor(5.7) in C, assuming proper inclusion of the math library”. This question is standard in competitive examination syllabi for Function.

To indicate that the function should be inlined by the compiler is the correct answer to “In C, what is the purpose of the 'inline' keyword when used with a function”. This question is standard in competitive examination syllabi for Function.

A value passed to a function when it's called is the correct answer to “What is a function parameter in C”. This question is standard in competitive examination syllabi for Function.

4 is the correct answer to “What is the result of the expression ceil(3.2) in C, assuming proper inclusion of the math library”. This question is standard in competitive examination syllabi for Function.

It specifies that the parameter is constant and cannot be modified is the correct answer to “In C, what is the purpose of the 'const' keyword when used with a function parameter”. This question is standard in competitive examination syllabi for Function.

Using the '...' notation is the correct answer to “How can you declare a function in C that takes a variable number of arguments”. This question is standard in competitive examination syllabi for Function.

To call the function itself is the correct answer to “In C, what is the purpose of the 'recursion' in a function”. This question is standard in competitive examination syllabi for Function.

8 is the correct answer to “What is the result of the expression pow(2, 3) in C, assuming proper inclusion of the math library”. This question is standard in competitive examination syllabi for Function.

To indicate that the function may change external variables is the correct answer to “What is the purpose of the 'volatile' keyword when used with a function in C”. This question is standard in competitive examination syllabi for Function.

Limited to the function where it is declared is the correct answer to “In C, what is a function parameter's scope”. This question is standard in competitive examination syllabi for Function.

All of the above is the correct answer to “Use of functions”. This question is standard in competitive examination syllabi for Function.

All of the above is the correct answer to “What is function”. This question is standard in competitive examination syllabi for Function.