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A brief introduction to C
Mohamed Elsayed
Head of Technical Committee IEEE
ZC

Before the programming language:
A circuit which adds two numbers
But one problem arises here. To be able to write a computer program by
typing out billions of 1s and 0s would require superhuman brainpower,
and even then it would probably take you a lifetime or two to write.

Using programming language:
You can say that any programming language is just like a
dictionary which contains words that mean certain circuits.
For example : addition, multiplication, etc.

Structure of a simple program :

Make the things simpler !
• #include <stdio.h> includes the standard input output library
functions. The printf() function is defined in stdio.h . (you can think of
a library as a dictionary contains words and their meanings)
• void main() The main() function is the entry point of every
program in c language. The void keyword specifies that it returns no
value. (It’ll be explained soon)
• printf() The printf() function is used to print data on the console.

What is #include <stdio.h>
• stdio stands for standard
input/output which contains
functions that help in the process of
input or output.
• It’s more or less like including a
dictionary which contains words and
their meanings (function and their
definition)
• Without it you cannot write printf()
because it will be meaningless to the
compiler.

Declaring variables :
int x;
int x = 5;
float x ;
float x = 3.3;
char x ;
char x = ‘F’;

printf
The syntax :
printf(“format string”,arguments_list);
Place holders can be %d(integer), %c(character), %s(string), %f(float)
• Example :
int x=50;
printf(“My number is integer and its value is %d”,x);

printf and ‘n’
Hello World
Hello World
Hello WorldHello World

Do you want to enter some input?
• Scanf is a function
• The syntax: scanf("%d", &a);

Do you have a compiler ?
Go to
• http://www.tutorialspoint.com/compile_c_online.php
• http://www.learn-c.org/

Semi-colon :
in C is like in English

Comments in C :
• Ignored by the compiler
• Are used to enhance the readability of your code

Example:
I go to the university ..
IF Else

If and if-else statement :
used to execute the code if condition is true or false.

The from of if-else statement:
if(condition1){
//code to be executed if condition1 is true
} else { // code to be executed if all the conditions are false
}

Examples: Try it yourself ..
The number is greater than 50 ! Here is the rest of
my program
Here is the rest of my program
Can you make the user enter the number
instead of writing it in the program ?

Operators to do complicated jobs :
• If (x>5&&x<10) // if x is greater than
5 and less than 10
• If (x==6||x==5) // if x is equal 6 or 5
• If(x!=6) // if x is not equal to 6

A brief introduction to C Language

For loop syntax:
•It is good if number of iteration is known by the user.
•Syntax:-
for(initialization;condition;incr/decr){
//code to be executed
}

Example: Try it yourself ..
The output :
The current value of x is 0

While loop :
while(condition){
//code to be executed
}
• It is better if number of iteration is not known by the user.

Break the loop under a certain condition !

Break statement:
it is used to break the execution of loop (while, do while and for) and
switch case.
Syntax:-
jump-statement;
break;

Function form :
• Syntax to call function:-
variable=function_name(arguments...);

A simple function : Try it yourself ..

Void in functions:
• It’s the function that doesn’t return
anything !
• It’s the function that doesn’t
take or return anything !

What’s next ?
CS50: Introduction to Computer Science Embedded Systems - Shape The World YouTube Tutorials

Arduino Program:
int main(void)
{
setup();
while (1) // infinite loop
loop();
return 0;
}
void setup(){
}
void loop (){
}
The main function which contains
calling 2 functions : setup and loop
The setup function which
will be called only one time
The setup function which
will be called only one time

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A brief introduction to C Language

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A brief introduction to C Language