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Programming : QBASIC
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Transcript of Programming : QBASIC
{ Introduction Interface Features Rules Data Types of Mode Keywords Commands Reminders Simple Activity
It was invented in 1963 at Dartmouth College
It is an interpreter which means it reads every line, translates it and lets the computer execute it before
reading another.
The founders are John George Kemeny and Tom Kurtzas
It is a user friendly language.
It is widely known and accepted programming
language.
It is one of the most flexible languages , as modification
can easily be done in already existing programs. Language is easy since the
variables can be named easily and uses simple English phrases with
mathematical expressions.
All Q-basic language are made up of series of statements, which are executed in the order in which they are written.
Every statements should have at least one Q-Basic command word. The words that BASIC recognizes
are called KEYWORDS.
All the command words have to be written using some standard rules , which are called “Syntax Rules”. Syntax is the grammar of writing the statement in a language. Syntax errors are generated when improper
syntax is detected.
Data is a collection of facts and figures that is entered into the computer through the keyboard. Data is of two types: Constant and Variable.
CONSTANT : Data whose value does not change
a) Numeric Constant : negative or positive numbers.b) Alphanumeric Constant : Numbers or alphabets
written within double qoutes.
Variable : Data whose value is not constant.
a) Numeric Variable : variable that holds a numeric constant for calculations.
b) Alphanumeric Variables : variable that holds an alphanumeric variable which cannot be
used for calculations.
1. Direct Mode : It accepts single line instructions from the user and the output is viewed as soon as enter key is pressed.
2. Program Mode : It is used to type program which is stored in the memory, They have line numbers.
V. Nuval | C. Repollo
1.) LIST is used to list the program on the screen.
2.) RUN is used to execute the program.
3.) LLIST is used to list the program as a hardcopy.
4.) LPRINt is used to get the output of the program on the hard copy.
5.) NEW is used to clear the memory of the existing program.
6.) SYSTEM is used to take you back to the dos prompt
7.) PRINT is used to view the display on the screen
8.) CLS is used to clear the screen.
9.) RME is used to show the position of the mistake.
10.) SAVE is used to save the program.
11.) LOAD is used to load the program from the disk to the memory.
1. CLS is used to clear the screen.
2. PRINT is used to display the output on the screen.
3. REM gives an explanation of the program or the statement in the program thereby making the program more understandable to do the reader.
4. LET assigns a value to a variable in a program.
5. END is used at the end of the program to signal ending.
6. INPUT allows the user to enter a value for the variable while running the program.
7. DELETE is used to delete a line number in a program.
A Q-Basic program consists of the lines containing:
1.) a line number
2.) A Q-Basic keyword like PRINT,END etc.
3.) Each program line begins with positive number.
4.) No two lines should have same numbers.
It is possible to overwrite lines with the new statements, but if you want to write
a totally new program , use a NEW command
Command is a special function that tells the Q-Basic interpreter to do something.
The PRINT command tells the Q-Basic interpreter to print something to the screen.
PRINT “HELLO WORLD”
FIRST PROGRAMMED WORDS IN THE
HISTORY.