Page 251 - Computer_Science_F5

Computer Science Variable declaration Scope of variables in C++
programming
Since variables represent a certain
type of data, then, if you want to use a Based on their scopes, variables in C++
variable in a program, you are supposed can be classified into three types. These
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to define its name and data type. That are local, global, and static variables.
system of expressing variables is known
as variable declaration. It is a call to the (a) Local variables
compiler to prepare a memory size for Local variables are declared within the
a variable in relation to its data type. function block or inside the compound
To declare a variable, use the following statement. The following Program
syntax: datatype variableName. Example 4.8 demonstrates variable
declaration in C++.
Example of variable declaration:
int x; Program Example 4.8:

double area; Variable declaration

char t;
function ()

x, area and t represent variable name, {
while int, double and char represent data int a;
types. double b;
}
Note: If two or more variables are of
the same data type, they can be
grouped as datatype variable1, Variables a and b are defined within the
variable2, ……., variablen;. For block of function, and they can only
example, int x, y, z; be accessed inside that block. Hence,
a and b represent local variables.

Initialising variables (b) Global variables
Initialising variables involves using the
equal sign “=” to assign a value to the Global variables are declared before the
variable. The following syntax is used main function main(). Such variables
to initialise variable: datatype variable can be applied to any function within
the program. Global variables are
= value;. also known as external variables.

The following Program Example 4.9
An example of variable initialization is demonstrates the use of global variables
int i = 56; in C++ program.

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Computer Science Form 5.indd 242 23/07/2024 12:33