C++ Variables: Data Types and Scope

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Questions and Answers

What is the primary purpose of a variable in programming?

To control the flow of a program.
To allocate temporary memory for data storage. (correct)
To execute mathematical operations.
To define the structure of a program.

Global variables can only be used inside the `main()` function.

False (B)

Which of the following data types typically occupies 8 bytes of memory?

`int`
`double` (correct)
`char`
`float`

Explain the difference between 'initialization at the time of declaration' and 'initialization after declaration'. Provide a code example for each.

Initialization at the time of declaration assigns a value when the variable is declared (e.g., <code>int x = 5;</code>). Initialization after declaration involves declaring the variable first and assigning the value later (e.g., <code>int x; x = 5;</code>). Signup and view all the answers

In C++, to output a floating-point number with a fixed precision of 2 decimal places, you would use `std::cout << std::fixed << std::__________ (2);`.

setprecision Signup and view all the answers

Match the arithmetic operator with its description.

<ul> <li>= Multiplication / = Division % = Modulus (remainder)</li> </ul> <ul> <li>= Addition</li> </ul> Signup and view all the answers

What is the purpose of relational operators in C++?

To compare two values and determine the relationship between them. (A) Signup and view all the answers

The logical AND operator (`&&`) returns true if at least one of the operands is true.

False (B) Signup and view all the answers

What is the effect of the `++` operator when used as a postfix increment (e.g., `x++`)?

It increments the variable after its value is used in the expression. (D) Signup and view all the answers

Explain why the output of a program that prints uninitialized variables might be unexpected.

Uninitialized variables contain whatever random data was already present in their memory locations. This random data is often referred to as 'garbage values.' Signup and view all the answers

The C++ statement `std::cout << "\n\t";` will produce a character followed by a character in the output.

newline, tab Signup and view all the answers

Which of the following is the correct syntax for a nested `if-else` statement in C++?

if (condition1) { if (condition2) { // code } else { // code } } else { // code } (B) Signup and view all the answers

A variable name in C++ can contain spaces.

False (B) Signup and view all the answers

What happens to the information stored in variables when a program exits or the computer is turned off?

The information is lost. (D) Signup and view all the answers

Write a C++ statement that increases the value of a `double` variable named `length` by 5.2.

length += 5.2; Signup and view all the answers

In C++, the data type that has no value is represented by the keyword _______.

void Signup and view all the answers

Which header file must be included to use the `setprecision` manipulator in C++?

<code>iomanip</code> (D) Signup and view all the answers

Relational operators can't be used to compare characters.

False (B) Signup and view all the answers

What will be the final value of `x` after executing the following code? `int x = 5; std::cout << x++;`

6 (C) Signup and view all the answers

Provide the C++ syntax to output the string `Hello, World!` to the console.

std::cout << "Hello, World!" << std::endl; Signup and view all the answers

The modulus operator, denoted by the symbol _______, returns the remainder of a division.

% Signup and view all the answers

Given `int x = 10, y = 5;`, what will be the value of `result` after executing `bool result = (x >= y);`?

true (C) Signup and view all the answers

The `if` statement must always be followed by an `else` statement.

False (B) Signup and view all the answers

What is the correct syntax, in C++, for an `if` statement that assigns 1 to `x` if `y` is equal to 100, otherwise assigns 0 to `x`?

if (y == 100) {x = 1;} else {x = 0;} (A) Signup and view all the answers

Explain the difference between local and global variables in terms of scope and lifetime.

Local variables are declared inside a function or block and can only be accessed within that scope; they exist only during the execution of that function or block. Global variables are declared outside any function and can be accessed from anywhere in the code; they exist for the entire duration of the program's execution. Signup and view all the answers

Flashcards

What is a variable?

A named memory location in RAM to store and retrieve data for mathematical and logical operations.

Variable Scope

Variables declared inside a function or block; Variables declared outside are called global