chapter 2 Variable Declaration and Scope Quiz2

What will happen if you try to use a variable that is not declared?

• It will be created automatically

• Syntax error

• Assigned value 0

• Stored as a constant

Answer explanation

In C++, all variables must be declared before they are used. If you try to use a variable without declaring it, the compiler will give an error because it doesn’t know the variable’s type or memory location.

Which of the following is a correct way to declare and initialize a float variable?

• float = 3.14;

• float pi = 3.14;

• 3.14 = float pi;

• declare float pi;

Answer explanation

The correct way to declare and initialize a float is by first stating the data type (float), then the variable name (pi), and then assigning a value (3.14). The other options use incorrect syntax.

What does variable scope refer to?

• The data type of the variable

• The location where the variable can be accessed

• The name of the variable

• The size of memory used

What is the difference between a local and a global variable?

• Local variables are always integers

• Global variables are only accessible in loops

• Local variables are declared inside functions, global outside all functions

• Global variables are deleted immediately after use

Answer explanation

Scope means where in the program you can use the variable. For example, a variable declared inside a function can only be used inside that function (local scope).

What is the output of this code?

• 50

• 25

• 0

• Error

Answer explanation

The num inside main() is a local variable with a value of 25. It hides (overrides) the global num with a value of 50. So, the program prints 25.