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Structured Programming - Lesson 1

Created: Monday, 12 August 2013 Written by Ehab Eldeeb

Data Types

Data Type is a reserved word for any programming language that tells the program what type of data you are using

• Integer (Whole Number) : int, short, long
• Floating Point (Fractions) : float, double
• Character (letter or symbol) : char
• For a whole word you will need to use "String" .. it will be covered later on in the next course "Programming Applications"

 

Identifiers

- An identifier is the name used for a data object (a variable or a constant), or for a function,  in a C program.
- Note that it's case-sensitive (Ehab is not ehab .. they are different)
- using meaningful identifiers is a good thing for yourself so you can understand what you are doing

an identifier must start with a letter or underscore .. you can't begin your identifier with a number, and be followed by zero or more letters
(A-Z, a-z), digits (0-9), or underscores

It's okay to use these examples for an identifier:

• age_of_person
• taxRateY2K
• PrintHeading
• ageOfHorse
• TeMpeRaTuRe

While it's NOT okay to use these words as identifiers:

• age# (symbols are not allowed)
• 2000TaxRate (Cannot start with a number)
• int (data types cannot be used as identifiers)

 

Place Holders

%d %f %lf %c ... what are those?

Example:
int age = 8;
printf( “ The age is %d years “, age );
     This will print out "The age is 8 years"
You will understand more when we get into writing an actual program

 

Escaping

\n .. New Line
Example: printf("My name is \n Ehab");
This will print out "My Name is " on a line, and "Ehab" on the line under it

\t .. tabbed space (Just like if you press "space" 5 times)

 

Comments

You can write a comment inside your program using this tag /* .......... */
Example: printf("Hello World"); /* Print out hello world message */
the comment "Print out hello world message" will be seen in the source code, but will not be displayed in the actual application

 

Example Program "Hello World"

#include <stdio.h>
#include <conio.h>

void main(){
printf("Hello World");
getch();
}

... That's it :D

One Last thing ... Programming Errors

Syntax errors : detected by complier

• Missing semicolons ;
• Undeclared variables,…etc

 

Run-time errors

• detected during execution. E.g. division by zero

 

Logical errors

• Due to faulty algorithm .. example "2 + 2" is written in the program variable1 - variable2

 

.... This was the introduction to C Programming
For sure, you will understand better in the lecture, this article is just for reference