PPT on Computers

8/13/2019 PPT on Computers

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OVERVIEW History of c

Program in c

Sample program Data types

Variables

Input/output

Control statements


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Fundamentals and History of C

C is developed by Dennis Ritchie

C is a structured programming language

C supports functions that enables easymaintainability of code, by breaking large file intosmaller modules

Comments in C provides easy readability

C is a powerful language


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PROGRAM STRCTURE IN C

#include

#includevoid main()

{

--other statements

}


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HEADER FILES The files that are specified in the include section is

called as header file

These are precompiled files that has some functionsdefined in them

We can call those functions in our program bysupplying parameters

Header file is given an extension .h C Source file is given an extension .c


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MAIN FUNCTION This is the entry point of a program

When a file is executed, the start point is the mainfunction

From main function the f low goes as per theprogrammers choice.

There may or may not be other functions written byuser in a program

Main function is compulsory for any c program


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Sample program#include

#include

int main(){

printf(Hello);

return 0;

}

This program prints Hello on the screen when weexecute it


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HOW TO RUN C PROGRAM

Type a program

Save it

Compile the program This will generate an exe file

(executable) Run the program (Actually the exe created out of

compilation will run and not the .c file)

In different compiler we have different option forcompiling and running. We give only the concepts.


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Points to remember

Case Sensitive

Case matters in C. A is not a

Add plenty of comments (/* */ or //)

Good layout, not:

main() {printf("Hello World\n");}

Use meaningful variable names

Initialize your variables Use parentheses to avoid confusion:

a=(10.0 + 2.0) * (5.0 - 6.0) / 2.0


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DATA TYPES Primitive data types

int, float, double, char

Aggregate data types Arrays come under this category

Arrays can contain collection of int or float or char ordouble data

User defined data types Structures and enum fall under this category.


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VARIABLESVariables are data that will keep on changing

Declaration

;int a;

Definition=;

a=10; Usage

a=a+1; //increments the value of a by 1


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RULES FOR VARIBLE NAME

Should not be a reserved word like int etc..

Should start with a letter or an underscore(_)

Can contain letters, numbers or underscore. No other special characters are allowed including

space

Variable names are case sensitive

A and a are different.


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INPUT & OUTPUT Input

scanf(%d,&a);

Gets an integer value from the user and stores it under

the name a

Output

printf(%d,a)

Prints the value present in variable a on the screen


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OPERATORSArithmetic (+,-,*,/,%)

Relational (,=,==,!=)

Logical (&&,||,!)

Bitwise (&,|)

Assignment (=)

Compound assignment(+=,*=,-=,/=,%=,&=,|=) Shift (right shift >>, left shift


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OPERATORS(Contd.)Increment and Decrement Operators

++ Increment operator-- Decrement Operator

k++ or k-- (Post-increment/decrement)

k = 5;

x = k++; // sets x to 5, then increments k to 6


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(contd.)

++k or --k (Pre-increment/decrement)

k = 5;x = ++k; // increments k to 6 and then sets to the

resulting value, i.e., to 6


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CONTROL STATEMENTS


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Conditional Statements

if (condition)

{stmt 1; //Executes if Condition is true

}

else{

stmt 2; //Executes if condition is false

}


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In this we have some if(conditions)

They are

1. if2. Simple if

3. if else

4. compound if

5. nested if


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SWITCH & BREAK

switch(var){

case 1: //if var=1 this case executes

stmt;

break;

case 2: //if var=2 this case executes

stmt;

break;default: //if var is something else this will execute

stmt;

}


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LOOPS


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FOR LOOP The syntax of for loop is

for(initialisation;condition checking;increment)

{

set of statements

}

Eg: Program to print Hello 10 times

for(I=0;I


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WHILE LOOP The syntax for while loop

while(condn)

{

statements;}

Eg:

a=10;

while(a != 0) Output: 10987654321

{printf(%d,a);

a- -;

}


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DO WHILE LOOP The syntax of do while loop

do

{

set of statements}while(condn);

Eg:

i=10; Output:

do 10987654321{

printf(%d,i);

i--;

}while(i!=0)


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THANKS

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PPT on Computers