Call By Value And Call By Reference In C Mcq Exercise 1

✅ Call by Reference transfers the input argument's actual contents onto the formally defined parameter when compared to Call by Value, which copies that argument's physical address onto the parameter.
✅ There have been no alterations.
✅ When the function is called by reference, it prevents the previous argument from being changed; when it is called by value, it does.

Explanation:

The correct answer is option (a). Call by Value copies the appropriate argument's real amount onto the parameter being called, whereas Call by Reference transfers the argument's physical address into a formal parameter.

Amongst the following suggestions, which of the following is true for Call by Reference in C?

✅ The function using the initial values.
✅ The function works with a copy of the original values.
✅ There is no difference between Call by Value and Call by Reference.
✅ Call by Reference is not possible in C.

Explanation:

The accurate solution is choice (a). This function operates using the initial values.

In the C language, the idea of "Call by Reference" is executed through the utilization of pointers. By passing a variable to a function by reference, you are providing the function with the memory address of the variable instead of a duplicate of its value. This grants the function the ability to access and alter the original variable directly.

What will be the result of the code snippet below?

Example


#include <stdio.h>
void swap(int a, int b) {
    int temp = a;
    a = b;
    b = temp;
}
int main() {
    int x = 10, y = 20;
    swap(x, y);
    printf("x = %d, y = %d", x, y);
    return 0;
}

✅ x = 20, y = 10
✅ x = 10, y = 20
✅ x = 0, y = 0
✅ Compilation error

Explanation:

The correct answer is option (b).

In C, passing parameters to functions by value is the standard practice. This means that duplicates of the specified variables are transferred to the swap function when it is invoked with x and y as arguments. To elaborate, invoking swap(x, y) creates local duplicates of x and y (named a and b, respectively) within the swapping function.

Within the swap function, the values of a and b undergo manipulation. A temporary variable, temp, is employed to hold the value of a. Subsequently, a takes on the value of b, and b is assigned the value stored in temp. It's important to note that these modifications exclusively impact the local versions of a and b within the swap function. The initial variables x and y in the main function are unaffected since the swap function operates on duplicates rather than the originals.

Upon the completion of the swap function, execution control transitions back to the main function. In this segment, the printf statement displays the unchanged values of x and y. Because the swap function did not modify x and y (owing to the Call by Value nature), their initial values persist: x = 10 and y = 20. Consequently, the program's output will be x = 10, y = 20.

What is the specific keyword utilized in C programming to enable Call by Reference functionality?

Explanation:

The accurate choice is alternative (b). Within the C programming language, pointers represent a robust capability enabling Call by Reference functionality. The * symbol, referred to as the dereference operator, is utilized to manipulate pointers.

The * operator represents the keyword that is employed in C programming for implementing Call by Reference. Communicating with pointers becomes an appealing characteristic, which permits functions to modify parameters outside of their respective positions immediate scope. The operator pointer is necessary for the above reason. A function is able to manipulate the numerical value of the variable function is directed towards directly when it is made to take a pointer as a parameter.

In Call by Reference, what is passed to the function?

✅ Copy of the variable
✅ Value of the variable
✅ Address of the variable
✅ None of the above

Explanation:

The accurate choice is alternative (c). Rather than just transferring a duplicate of the variable or its value to the invoked function, call by Reference transmits the memory address of the variable. This illustrates that the function receives a reference to the location in memory where the real parameter is stored, as opposed to duplicating the value of the variable for manipulation.

The * operator in C indicates this pointer, and it allows the function to retrieve and modify the value of the initial parameter directly. Whatever modifications are made to a constant inside the function are mirrored within the original variable outside the function by utilizing the power source address-of operator (&) to get the address of the variable as well as sending this address to the function.

Which of the following is a benefit of Call by Reference?

✅ It saves memory space.
✅ It ensures that the function cannot modify the actual arguments.
✅ It allows the function to modify the original variables.
✅ It is easier to implement than Call by Value.

Explanation:

The correct answer is option (c). One of the primary benefits of using Call by Reference is that it allows the function to directly modify the original variables, which is particularly useful when changes need to be reflected to the caller. This capability is achieved by passing the memory address of the variable to the function rather than a copy of its value. When the function receives the address, it can use pointers to access and modify the value stored at that address. As a result, any changes made to the variable within the function persist after the function call, directly affecting the original variable in the caller's scope.

Which of the following statements is true regarding Call by Value and Call by Reference in C?

✅ Call by Value allows the function to modify the caller's variable directly.
✅ Call by Reference passes a copy of the variable's value to the function.
✅ Call by Value involves passing the address of the variable to the function.
✅ Call by Reference allows the function to modify the caller's variable directly.

Explanation:

The correct answer is option (c). In C, Call by Value passes a copy of the variable's value to the function, meaning any modifications inside the function do not affect the original variable. Conversely, Call by Reference passes the address of the variable, enabling the function to access and modify the actual variable directly. This allows the function to have a direct impact on the variable's value in the caller's scope.

Which of the following is a characteristic of Call by Reference in C?

✅ It makes a copy of the actual argument.
✅ It allows the function to modify the original argument.
✅ It is used to prevent the modification of the original argument.
✅ It is not possible in C.

Explanation:

The correct answer is option (b). Call by Reference allows the function to modify the original argument by passing the address of the variable to the function.

Which of the following statements is true about Call by Value?

✅ Changes made to the parameter inside the function reflect in the original variable.
✅ A copy of the actual parameter's value is passed to the function.
✅ The function receives the address of the variable.
✅ Call by Value is not supported in C.

Explanation:

The right choice is alternative (b). Call by Value entails sending a duplicate of the value of the real parameter to the function. This duplication enables the function to manipulate its unique local version of the data without impacting the initial variable.

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