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QBASIC: A Tool For Modern Programming

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Gifty Belle Manaois
Gifty Belle Manaois

This document provides an overview of the QBASIC programming language and its commands. It discusses QBASIC's interpreter-based execution model and use of line numbers. It also covers basic QBASIC concepts like constants, variables, and commands for printing, clearing screens, and running programs. The document then examines specific commands in more detail, such as PRINT, INPUT, IF/THEN, ELSE, and ELSEIF. It provides examples of how to use expressions, variables, and conditional logic in QBASIC programs.

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QBASIC: A TOOL FOR MODERN PROGRAMMING BY REDEN R. PATACSIL AND GIFTY BELLE MANAOIS
Beginners All Purpose Symbolic Instruction Code (BASIC) is an interpreter which means it reads every line, translate it and lets the computer execute it before reading another. Each instruction starts with a line number. RULES IN USING QBASIC Statements to be made should be in proper sequence. Each statement should have one BASIC command which are called keywords. QBASIC has standard rules which are called Syntax.
QBASIC Data CONSTANT- data whose values does not change or remains fixed. NUMERIC CONSTANT numbers used for mathematical calculations. ALPHANUMERIC CONSTANT number or alphabets in double quotes. VARIABLE data whose values change depending on calculations executed by the program. NUMERIC VARIABLE variable that holds numeric constant. ALPHANUMERIC VARIABLE number or alphabets in double quotes.
CLS used to clear the screen. PRINT used to display the output on the screen. REM stands for REMARK. It gives an explanation of the program thereby making the program more understandable. LET assigns a value to a variable in a program. END it is usually given at the end of the program. INPUT allows users to enter values for a variable while running a program. DELETE <LINE NO.> - delete a line number in a program RUN used to execute the program and get the output on the screen. NEW used to totally write a new program. SYSTEM used to exit the QBASIC program. QBASIC Commands
PRINT Command The PRINT command tells QBASIC to print something to the screen. With the PRINT command, we can print numbers and letters to the screen. EXAMPLE:
PRINT Command If you pass an expression to the PRINT command, the value returned is printed. EXAMPLE: If you enclose the expression with quotation marks, the expression becomes a string and is not evaluated. EXAMPLE:
PRINT Command To place World onto the previous line, place a semi-colon after Print Hello. If you put a comma instead of a semi-colon on the first line, the program will insert spaces between two words.
Variables A variable is a piece of data kept in the computers memory. A variable is assigned to a letter(s) in the following way:
INPUT Command INPUT- allows the user to enter either a string or a number, which is then stored in a variable. If semi-colon (;) is used, the output will display a question mark (?). If a comma (,) is used, the output will display blank or nothing.
INPUT+PRINT Command The INPUT and the PRINT command can be used to utilize the variable in the INPUT command in computations in the PRINT command.
IF & THEN Command The IF and THEN commands are used to compare an expression and then perform some task based on that expression.
IF & THEN Command EXPRESSION SIGNS You can also enter the following statements, instead of the equal sign:
IF & THEN Command EXPRESSION SIGNS We can also combine signs.
ELSE Command Using the ELSE command, you can have the program perform a different action if the statement is false. EXAMPLE:
The following program uses ELSE with the END IF command: ELSE Command
ELSE IF Command The ELSE IF command allows you to perform a secondary action if the first expression was false. Unlike ELSE, this task is only performed if a specified statement is true.
You can have multiple ELSEIF commands, along with ELSE. ELSE IF Command
MULTIPLE EXPRESSIONS You can have more than one expression in IF THEN by using either the OR operator or the AND operator. The OR operator only requires one expression to be true in order to print Yes in the following program: The AND operator requires both expressions to be true.
THANK YOU! REDEN R. PATACSIL & GIFTY BELLE MANAOIS

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QBASIC: A Tool For Modern Programming

  • 1. QBASIC: A TOOL FOR MODERN PROGRAMMING BY REDEN R. PATACSIL AND GIFTY BELLE MANAOIS
  • 2. Beginners All Purpose Symbolic Instruction Code (BASIC) is an interpreter which means it reads every line, translate it and lets the computer execute it before reading another. Each instruction starts with a line number. RULES IN USING QBASIC Statements to be made should be in proper sequence. Each statement should have one BASIC command which are called keywords. QBASIC has standard rules which are called Syntax.
  • 3. QBASIC Data CONSTANT- data whose values does not change or remains fixed. NUMERIC CONSTANT numbers used for mathematical calculations. ALPHANUMERIC CONSTANT number or alphabets in double quotes. VARIABLE data whose values change depending on calculations executed by the program. NUMERIC VARIABLE variable that holds numeric constant. ALPHANUMERIC VARIABLE number or alphabets in double quotes.
  • 4. CLS used to clear the screen. PRINT used to display the output on the screen. REM stands for REMARK. It gives an explanation of the program thereby making the program more understandable. LET assigns a value to a variable in a program. END it is usually given at the end of the program. INPUT allows users to enter values for a variable while running a program. DELETE <LINE NO.> - delete a line number in a program RUN used to execute the program and get the output on the screen. NEW used to totally write a new program. SYSTEM used to exit the QBASIC program. QBASIC Commands
  • 5. PRINT Command The PRINT command tells QBASIC to print something to the screen. With the PRINT command, we can print numbers and letters to the screen. EXAMPLE:
  • 6. PRINT Command If you pass an expression to the PRINT command, the value returned is printed. EXAMPLE: If you enclose the expression with quotation marks, the expression becomes a string and is not evaluated. EXAMPLE:
  • 7. PRINT Command To place World onto the previous line, place a semi-colon after Print Hello. If you put a comma instead of a semi-colon on the first line, the program will insert spaces between two words.
  • 8. Variables A variable is a piece of data kept in the computers memory. A variable is assigned to a letter(s) in the following way:
  • 9. INPUT Command INPUT- allows the user to enter either a string or a number, which is then stored in a variable. If semi-colon (;) is used, the output will display a question mark (?). If a comma (,) is used, the output will display blank or nothing.
  • 10. INPUT+PRINT Command The INPUT and the PRINT command can be used to utilize the variable in the INPUT command in computations in the PRINT command.
  • 11. IF & THEN Command The IF and THEN commands are used to compare an expression and then perform some task based on that expression.
  • 12. IF & THEN Command EXPRESSION SIGNS You can also enter the following statements, instead of the equal sign:
  • 13. IF & THEN Command EXPRESSION SIGNS We can also combine signs.
  • 14. ELSE Command Using the ELSE command, you can have the program perform a different action if the statement is false. EXAMPLE:
  • 15. The following program uses ELSE with the END IF command: ELSE Command
  • 16. ELSE IF Command The ELSE IF command allows you to perform a secondary action if the first expression was false. Unlike ELSE, this task is only performed if a specified statement is true.
  • 17. You can have multiple ELSEIF commands, along with ELSE. ELSE IF Command
  • 18. MULTIPLE EXPRESSIONS You can have more than one expression in IF THEN by using either the OR operator or the AND operator. The OR operator only requires one expression to be true in order to print Yes in the following program: The AND operator requires both expressions to be true.
  • 19. THANK YOU! REDEN R. PATACSIL & GIFTY BELLE MANAOIS