![IDENTIFIERS / VARIABLES
▰ Identifiers may consists of:
❑ Letters (a-z, A-Z)
❑ Digits [0-9]
❑ Underscore “_”
▰ Identifiers
❑ Can begin only with a letter or an underscore
❑ Cannot be a C# keyword
3](https://image.slidesharecdn.com/week08-identifier-231008234208-a585f967/85/Week-08-Identifier-pdf-3-320.jpg)
![Declaring Variables
▰ When declaring a variable we:
❑ Specify its type
❑ Specify its name (called identifier)
❑ May give it an initial value
▰ The syntax is the following:
▰ example
5
<data_type> <identifier> [= <initialization>];
int height = 200;](https://image.slidesharecdn.com/week08-identifier-231008234208-a585f967/85/Week-08-Identifier-pdf-5-320.jpg)
Week 08 - Identifier.pdf
- 2. What is variable? ▰ A variable is a: ❑ Placeholder of information that can usually be changed at run-time ▰ Variables allow you to: ❑ Store information ❑ Retrieve the stored information ❑ Manipulate the stored information 2
- 3. IDENTIFIERS / VARIABLES ▰ Identifiers may consists of: ❑ Letters (a-z, A-Z) ❑ Digits [0-9] ❑ Underscore “_” ▰ Identifiers ❑ Can begin only with a letter or an underscore ❑ Cannot be a C# keyword 3
- 4. Variable (cont…) ▰ No other special characters are allowed including space ▰ Variable names are case sensitive ❑ A and a are different. ▰ Identifiers ❑ Should have a descriptive name ❑ Should be neither too long nor too short 4
- 5. Declaring Variables ▰ When declaring a variable we: ❑ Specify its type ❑ Specify its name (called identifier) ❑ May give it an initial value ▰ The syntax is the following: ▰ example 5 <data_type> <identifier> [= <initialization>]; int height = 200;
- 6. Variable (cont…) ▰ Variables are data that will keep on changing ▰ Declaration <<Data type>> <<variable name>>; int a; ▰ Definition <<varname>>=<<value>>; a=10; ▰ Usage <<varname>> a=a+1; //increments the value of a by 1 6
- 7. Variable (cont…) ▰ Examples of correct identifiers: ▰ Examples of incorrect identifiers: 7 int New = 2; // Here N is capital int _2Pac; // This identifiers begins with _ string nosApab = “Hello”; // Unicode symbols used // The following is more appropriate: string greeting = “Hello”; int n= 100; // Undescriptive int numberOfClients = 100; // Descriptive // Overdescriptive identifier: int numberOfPrivateClientOfTheFirm = 100; int new; // new is a keyword int 2Pac; // cannot begin with a digit
- 8. Declaring (cont…) ▰ Computers are machines that process data ❑ Data is stored in the computer memory in variables ❑ Variables have name, data type and value. ▰ Example of variable definition and assignment in C# int counter = 5; 8 Variable name Variable value Data type Assignment operator
- 9. Declaring (cont…) ▰ Examples of variable declarations: int myAge = 25; ▰ The equal sign (=) is an assignment operator ▰ The assignment operator works from right to left ▰ An assignment made when a variable is declared is an initialization ▰ It is not necessary to initialize a variable during a declaration. ▰ For example int myAge; is a valid declaration 9
- 10. Declaring (cont…) ▰ Examples of multiple variable declarations: ▻ int myAge = 25; int yourAge = 19; ▻ int myAge = 25, your Age = 19; ▰ Declarations of variables of the same type can be separated by commas. However, separate statements are used when declaring variables of different types ▻ int myAge, yourAge; double mySalary, yourSalary; 10
- 11. Displaying Variable Values ▰ You can display variable values by using the variable name within a WriteLine() method call 11
- 12. Displaying (cont…) ▰ Program that displays a string and a variable value 12
- 13. THANKS! Any questions? You can find me at delfirome@gmail.com