a brief introduction to c language

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.

Article to read ..

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.

Data Types:

Declaring variables :

int x;int x = 5;float x ;float x = 3.3;char x ;char x = ‘F’;

printfThe 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 WorldHello 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

Making decisions ?

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

It might be more branched ..

Loops are all around us !

The structure of a loop:

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 }

For loop :

Example: Try it yourself ..The output :The current value of x is 0The current value of x is 1The current value of x is 2The current value of x is 3The current value of x is 4The current value of x is 5The current value of x is 6The current value of x is 7The current value of x is 8The current value of x is 9

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

Example: Try it yourself ..

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;

Example:

Functions:

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

An Arduino program: