Note on Elements of QBASIC programming

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To construct the QBASIC program, we have to arrange some standard elements.The elements used in Qbasic are as follows:

  • Character set
  • Variables
  • Constants
  • Operator and Operands
  • Expression
  • Statements

Character Set

QBASIC has the character set consisting of the following elements:

  1. Alphabets: A, B, C,....Z
  2. Digits: 0, 1, 2........,9 and
  3. Special characters: + - * / ( ) . , $ ; ,: ,= ,> ,< , ^

The symbol ^ (caret) is used to denote exponentiation operator, the symbol * (asterisk) is used to denote multiplication and other symbols; have their usual meanings.

Constants

A quantity in a computer program which does not change its value during the execution of the program is called a constant. QBASIC allows the following constants:

  • Numeric constant

    The numeric constant is one that is formed by a sequence of digits 0, 1, 2,.....9 and may include a decimal point. A numeric constant may be an integer or a real number. 383, +57, 0, -6.2 and 6.15E4 are valid numeric constants. The number 6.15E4, in fact, represent 6.15 * 104. The notation E is used to represent the exponential form. The number after E is the exponent which can be positive or negative. However, its length cannot exceed two digits.

    It is also important to keep in mind that:

    • QBASIC does not distinguish between an integer and fraction.
    • Commands are not allowed in a numeric constant.
    • The limit on the number of digits that can be used varies from computer to computer. Normally, a numeric constant can have up to a maximum of eight digits.
  • String constant

    A string constant consists of a sequence of characters which must be enclosed by a quotation mark.

Variables

The quantity which may change its values during the execution of the program is called the variable.

In QBASIC, variables are also of two types:

  • Numeric variable: Numeric variable can assume numeric value and is represented by an alphabet or an alphabet followed by another alphabet or digit. For example A, C, A2, ABC, A6 etc, represent numeric variables.
  • String variable: A string variable is represented by an alphabet followed by dollar ($) sign. It should be kept in mind that while constructing the string variable, dollar ($) should be the last character. For example, B1$, NAME$, BOOK1$, etc are valid string variables.


Expression

An expression can be a string, or numeric constant, a variable or a combination of constants, variables with operators which returns a single value.

Operands

Operands are the data or variables on which mathematical, logical and string operations take place.

Operators

Operators are the symbols, which are used in arithmetic operations, logical expressions, and string expressions.

Statements

A statement is a set of instructions written using keywords or commands of QBASIC. Every programming language uses keywords as a statement with certain syntax.

  • To construct the QBASIC program, we have to arrange some standard elements.
  • A quantity in a computer program which does not change its value during the execution of the program is called a constant.
  • The quantity which may change its values during the execution of the program is called a variable.
  • A numeric variable can assume numeric value and is represented by an alphabet or an alphabet followed by another alphabet or digit.
.

Very Short Questions

A quantity in a computer program which does not change its value during the execution of the program is called a constant and the quantity which may change its values during the execution of the program is called variable. QBASIC allows the following constants:

  • Numeric constant
  • String constant

Numeric constant is one that is formed by a sequence of digits 0, 1, 2,.....9 and may include a decimal point. A numeric constant known as number may be integer or a real number. 383, +57, 0, -6.2 and 6.15E4 are valid numeric constants. The number 6.15E4, in fact represent 6.15 * 104. The notation E is used to represent exponential form. The number after E is the exponent which can be positive or negative. However, its length cannot exceed two digits.

In QBASIC, variables are also of two types:

  • Numeric variable
  • String variable

Numeric variable

Numeric variable can assume numeric value and is represented by an alphabet or an alphabet followed by another alphabet or digit. For example A, C, A2, ABC, A6 etc. represent numeric variables. A string variable is represented by an alphabet followed by dollar ($) sign. It should be kept in mind that while constructing the string variable, dollar ($) should be the last character. For example: B1$, NAME$, BOOK1$, etc are valid string variables.

The elements used in Qbasic are as follows:

  • Character set
  • Variables
  • Constants
  • Operator and Operands
  • Expression
  • Statements

A statement is a set of instructions written using keywords or commands of QBASIC.

Operators are the symbols, which are used in arithmetic operations, logical expressions and string expressions.

Operands are the data or variables on which mathematical, logical and string operations take place.

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  • The symbol ^ (caret) is used to denote ___________.

    usual meanings


    multiplication


    division


    exponentiation operator


  • A quantity in a computer program which does not change its value during the execution of the program is called a ___________.

    commands


    variables


    constants


    operation


  • Which of the following consists of a sequence of characters which must be enclosed by a quotation mark?

    Exponential Operators


    Numeric Constants


    String Constant


     Variables


  • Which of the following is is represented by an alphabet followed by dollar ($) sign ?

    String constants


    Numeric variable


    String variable


    Numeric constants


  • _________can be a string, or numeric constant, a variable or a combination of constants, variables with operators which returns a single value.

    Code


    Operators


    Commands


    Expression


  • ____________ is a set of instructions written by using keywords or commands of QBASIC.

    Statements


    Expression


    Commands


    Code


  • _________ are the symbols, which are used in arithmetic operations, logical expressions and string expressions.

    Code


    Commands


    Operators


    Operands


  • NAME$ is an example of:

    Numeric variable


    String constants


    Numeric constants


    String variable


  • You scored /8


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