QBASIC

Ch-6    First step in programming

Program:- it is a set of instructions.

Programming language:- A language which is used to making a program is known as a programming language.

► C++, c, java, python...etc are the example of programming language.

QBASIC:- it is the programming language which is used to develop a small program.

► BASIC stands for beginners all-purpose symbolic instruction code.

► It was developed by professor Jhon G. Kemeny and Thomas E. Kurtz of Dartmouth college in USA.

► This is for beginners and was implemented in the 1960’s.

 

Elements of programming language

Character set:- it is a set of symbols that consists of digits , letters and special characters. Where digit is zero(0) to nine(9) , letters is A to Z and special character is +,-,/,%,< ,>,=,() , ; ,:,!,$,#,?.

Constants :- the value does not change during program execution is known as constants.

There are two categories of constant such as-

1.    Numeric constant

2.    String constant

 

1.    Numeric constant :- A constant on which mathematical operations such as addition, subtraction, division, multiplication , etc can be take place is known as numeric constant.

Ø It consists of digits (positive and negative number) .

Ø It can be of two types such as :-

¦ Integer type- 1,234, 456,.......etc.

¦ Real number type – 7.8, 0.765....etc.

 

2.    String constant :- A constant , on which mathematical calculation cannot be done is said as string constant

Ø It consists of digits , letters or other characters.

Ø It is also known as alphanumeric or non-numeric constants.

Ø These are always enclosed within double quotes.

Ø In BASIC programming language, the value of string may be up to 255 characters long.

Ø Examples – “vikasmishra” , “vmsmproramming”,  “1234”

 

Variable :- A value which can be change during program execution is known as variable.

► Variable is a location in the computer memory and within program that can be referred by a name and whose values can be change during program execution.   

► There are two categories of variable such as-

1.    Numeric variables

2.    String variables  

 

1.    Numeric variables :- A variable which stores a numeric value is known as numeric variable.

¦ It is the memory location that stores numbers.

¦ Example  -  vmsm=20 where vmsm is a name of variable and equal sign(=) is an assignment operator and 20 is numeric  value .

¦ The name of numeric variable should not contain any special character and there should not be any space between two characters.

¦ The maximum number of characters in a numeric variable is 1 to 8 characters.

¦ The first character of variable should be letter.

¦ It may consists both letters or numbers.

 

String variables :- The memory location or variable that stores letters or words is called as String variable.

► The name of string variable always ends with a dollar ($) sign.

► Example- name$=”vmsm”.

► String is used to store alphabets , words, specials characters  or theirs combinations.