Question

Mark the following statements as true or false: a. To use a predefined function in a program, you need to know only the name of the function and how to use it. b. \(A\) value-returning function returns only one value. c. Parameters allow you to use different values each time the function is called. When a return statement executes in a user-defined function, the function immediately exits. e. A value-returning function returns only integer values. I. A function that changes the value of a reference parameter also changes the value of the actual parameter. a. A variable name cannot be passed to a value parameter. h. If a \(\mathrm{C}++\) function does not use parameters, parentheses around the empty parameter list are still required. I. In \(C++,\) the names of the corresponding formal and actual parameters must be the same. I. Whenever the value of a reference parameter changes, the value of the actual parameter changes. k. In \(\mathrm{C}++,\) function definitions can be nested; that is, the definition of one function can be enclosed in the body of another function. I. Using global variables in a program is a better programming style than using local variables, because extra variables can be avoided. m. In a program, global constants are as dangerous as global variables. n. The memory for a static variable remains allocated between function calls.

Short answer

a. False, b. True, c. True, d. True, e. False, f. True, g. False, h. True, i. False, j. True, k. False, l. False, m. False, n. True.

Step-by-step solution

Understanding Function Usage

a. To use a predefined function in a program, you need to know not only the name, but also its parameters and how to call it properly. Thus, this statement is **false**.

Value-Returning Functions

b. A value-returning function in programming can return only one value. Hence, this statement is **true**.

Parameters and Function Calls

c. Parameters allow a function to be flexible and take different inputs each time it is called. Therefore, this statement is **true**.

Function Exit on Return

d. When a return statement is executed in a function, it immediately exits the function. This makes the statement **true**.

Function Return Types

e. A value-returning function can return various types, not just integers. Thus, the statement is **false**.

Reference Parameter Effects

f. A function changing a reference parameter's value will alter the actual parameter's value, making this statement **true**.

Passing Variables by Value

g. A variable name can indeed be passed to a function as a value, making this statement **false**.

Use of Parentheses in Function Declaration

h. In C++, even if no parameters are used, parentheses are required in function declarations, making the statement **true**.

Parameter Naming Requirements

i. C++ does not require that the formal and actual parameter names match; hence, this statement is **false**.

Reference Parameter Alterations

j. When a reference parameter changes, the actual parameter's value changes too. This statement is **true**.

Nested Function Definitions in C++

k. C++ does not support function definitions within other function bodies, rendering this statement **false**.

Global vs Local Variables

l. Global variables are not better than local variables for programming style because they can lead to more complex and error-prone code. So, this is **false**.

Global Constants vs Variables

m. Global constants are less risky than global variables as they are immutable and cannot lead to unexpected side-effects, so the statement is **false**.

Static Variable Memory Retention

n. Static variables retain their memory allocation and value between calls, making this statement **true**.

Key concepts

Understanding Value-Returning Functions

In C++, a value-returning function is a function designed to return a single value as its output. This functionality is crucial as it allows a program to use the result of a computation directly. For instance, a simple function to add two numbers might look like this: ```cpp int add(int a, int b) { return a + b; } ``` The `add` function here takes two integers as parameters and returns the sum as an integer. Keep in mind that a value-returning function can return any data type—not just integers. They can return floats, characters, objects, or even other functions. The return type must be specified in the function definition.

• Value-returning functions can only return one value at a time.
• They act like expressions and can be used in larger equations or decision statements.

Using value-returning functions efficiently is a fundamental programming skill that helps organize code and reuse computations across different parts of the program.

Reference Parameters Unpacked

In C++, reference parameters provide a method for a function to access and modify the actual variables passed to it. When a parameter is passed by reference, the function works with the original data rather than a copy. Consider this example: ```cpp void swap(int &x, int &y) { int temp = x; x = y; y = temp; } ``` Here, the `swap` function modifies the actual variables provided to it by swapping their values using reference parameters `x` and `y`.

• Reference parameters use the `&` symbol in the function prototype to indicate that they should work with the actual memory address of the variable.
• The values of reference parameters affect the original variables, ensuring any changes are reflected globally in the area they are used.

Reference parameters are beneficial when large data structures need to be modified without the overhead of copying them.

Global vs Local Variables Explained

A significant aspect of C++ programming involves understanding the scope and lifetime of variables, categorized into global and local variables.

• Global variables are declared outside of any function, typically at the top of a file, and can be accessed by any part of the program. They remain in memory for the program's entire execution.
• Local variables are declared within a function and can only be accessed within that function. They are created upon entry and destroyed upon exit of the function.

While global variables can be handy for sharing data among multiple functions, they come with risks, such as unintended side-effects and making the code difficult to debug. Local variables, on the other hand, increase modularity and reduce the chances of errors by limiting variable access. In general, promoting the use of local variables is considered better practice as it narrows down the areas where a variable might be modified, simplifying maintenance and debugging.

Static Variables in C++

Static variables in C++ are unique because they maintain their value even after the function in which they're defined returns. This feature makes them particularly useful in scenarios where a function needs to remember the result of a computation between different calls. For example: ```cpp void countCalls() { static int count = 0; ++count; std::cout << "Function has been called " << count << " times." << std::endl; } ``` Here, the variable `count` is static, so it retains its new value each time `countCalls` is invoked, providing a running count of calls.

• Static variables are initialized only once, when the function is first called, and they retain their values between calls.
• They can be used to preserve state information across multiple function invocations.

Although powerful, static variables should be used judiciously as they can introduce hidden dependencies across function calls, making the program harder to understand and maintain unless clearly documented.