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C - Introduction

Ramiz Ahmed

(Trainer)

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What Is C

Currently, the most commonly-used language forembedded systems.

High-level assembly.

Very portable: compilers exist for virtually everyprocessor.

Easy-to-understand.

Produces efficient code

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History

Developed between 1969 and 1973 along with Unix.

Due mostly to Dennis Ritchie.

Designed for systems programming -

Operating systems. Mobile devices like cellular phones and

palmtops. 3D computer games.

Hardware devices. Common consumes devices like microwave

ovens, washing machines and digitalcameras.

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C character set

Alphabets A,B,.... Y,Za,b,.... y,z

Digits 0,1,2,3,4,5,6,7,8,9

Special Symbols ~ ! @ # $ % & * ( ) _ = +[ ] \ { } : ; ' < > , . ? /

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Constants and Variables

Constant is an entity that doesn't change. Variable is an entity that may change.

Location whose name is x can hold different values at adifferent times x is known as a variable.As again this 3 or

5 do not change, hence are known as constants.

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Types of constants

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Rules for constructing integerconstants

1. An integer constant must have at least one digit.

2. It must not have a decimal point.

3. It can be either positive or negative.

4. If no sign precedes an integer constant it is assumed to be

positive.

5. No commas or blanks are allowed within an integer constant.

6. The allowable range for integer constants is

2147483648 to +21474836477. Size = 4 bytes.

For Example 426 , -8000

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Rules for constructing realconstants

A real constant must have at least one digit.

It must have a decimal point.

It could be either positive or negative.

Default sign is positive. No commas or blanks are allowed within a real constant.

Size = 4 bytes.

Ex.: +325.34

426.0

-32.76

-48.5792

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The mantissa part and the exponential part should be separated by aletter e.

The mantissa part may have a positive or negative sign.

Default sign of mantissa part is positive.

The exponent must have at least one digit, which must be a positive ornegative integer.

Default sign is positive.

Range of real constants expressed in exponential form is -3.4e38 to3.4e38.

Ex.: +3.2e-54.1e8

-0.2e+3

-3.2e-5

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Rules for constructing characterconstants

A character constant is a single alphabet, asingle digit or a single special symbol enclosedwithin single inverted commas. Both the invertedcommas should point to the left. For example, Ais a valid character constant whereas A is not.

The maximum length of a character constant canbe 1 character.

Range -128 to +127

Ex.: 'A' , 'I' , '5'

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Rules --A variable name is any combination of 1 to 31

alphabets, digits or underscores.The first character in the variable name must be an

alphabet or underscore.No commas or blanks are allowed within a variablename.No special symbol other than an underscore (as in

gross_sal) can be used in a variable name.

Ex.: si_intm_hrapop_e_89

These rules remain same for all the types of primary and

secondary variables.

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C keywords

There are only 32 keywords available in C.The keywords cannot be used as variable namesbecause if we do so we are trying to assign a newmeaning to the keyword, which is not allowed by

the computer.It would be safer not to mix up the variable namesand the keywords.

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Hello World in C

#includevoid main(){

printf(Hello, world!\n);}

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Simple interest Example in C

/* Calculation of simple interest */main( ){int p, n ;

float r, si ;p = 1000 ;n=3;r = 8.5 ;

/* formula for simple interest */si = p * n * r / 100 ;printf ( "%f" , si ) ;}

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Getting values from user

#includeInt main(){int p,n;Float r,si;printf(Enter values of Principle,NOI,ROI);scanf(%d%d%f,&p&n&r);

si=p*n*r/100;printf(simple interest=%f);Return 0;}

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C Instructions

Type declaration instruction To declare the typeof variables used in a C program.Arithmetic instruction To perform arithmeticoperations between constants and variables.Control instruction To control the sequence ofexecution of various statements in a C program.

C ti

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Type declaration instruction

Int a;Float b;Char name;

Arithmatic instruction* , / , - , +

Arithmatic operations can be performed on int's,

float's and char'sChar x,y;Int z;X='a'; y='b';

z=x+y; /* a and b are 97 and 98*/

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Conversion integer to float

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Type conversion in assignments

K is an integer and a is real variable.

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Hierarchy of operations

The priority or precedence in which the operations in an arithmeticstatement are performed is called the hierarchy of operations.

I=2*3/4+4/4+8-2+5/8

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THANK YOU