5. INTRODUCTION TO C
C LANGUAGE WAS DESIGNED BY “DENNIS
RITCHIE IN 1972 at AT & T BELL LABORATORIES
C IS A STRUCTURED PROGRAMMING
LANGUAGES
IT IS USED TO DESIGN DIFFERENT
APPLICATIONS
C ++ IS AN EXTENSION OF C LANGUAGE
C ++ WAS DESIGNED BY “BJARNE
STROUSTRUP” IN 1980
5
7. TOKENS: INDIVIDUAL ELEMENTS OF A PROGRAM
SIX TYPES OF TOKENS
IDENTIFIERS
KEYWORDS
CONSTANTS
OPERATORS
SPECIAL CHARACTERS
STRINGS
7
8. IDENTIFIERS:
ELEMENT IN A C PROGRAM IS GIVEN A NAME
CALLED AN IDENTIFIER.
RULES OF IDENTIFIER:
IT SHOULD CONTAIN ALPHABETS: a-z and A-Z
NUMBERS 0 TO 9
UNDERSCORE ( _ )
STARTING CHARACTER OF AN IDENTIFIER
SHOULD BE ALWAYS ALPHABET
8
9. KEYWORDS:
KEYWORDS ARE RESERVED WORDS USED IN A
PROGRAM THAT HAVE SPECIAL MEANING
ALREADY DEFINE TO COMPILER
9
auto double int struct const float short unsigned
break else long switch continue for signed void
case enum register typedef default goto sizeof volatile
char extern return union do if static while
10. CONSTANT: THE VALUE IS FIXED AND
CANNOT BE CHANGED DURING PROGRAM
EXECUTION
10
11. OPERATORS: A SYMBOL THAT GIVES AN
INSTRUCTION TO PERFORM DIFFERENT TYPES
OF OPERATIONS
11
TYPES OF OPERATOR SYMBOLS EXAMPLE
ARITHMETIC OPERATOR +,-,*,/,% A+B
RELATIONAL OPERATOR >,<,>=,<=,==,!= A>B
LOGICAL &&,||,!= A && B
INCREMENT &
DECREMENT
++ AND-- A++
A--
ASSIGNMENT = A=A+B
BITWISE &,|,^,>>,<<,~ A>>B
COMMA OPERATOR , A,B
CONDITIONAL ?: A?B
12. SPECIAL CHARACTERS: ALL THE CHARACTERS
OTHER THAN a to z A TO Z AND O to 9 ARE
SPECIAL CHARACTERS
STRING: A STRING IS A GROUP OF
CHARACTERS ENCLOSED IN DOUBLE QUOTES
12
TYPES CHARACTER SET
LOWER CASE a-z
UPPER CASE A-Z
DIGITS 0 TO 9
SPECIAL CHARACTERS !,@,#,$%,^,&,*
13. DATA TYPE: A DATA TYPE DEFINES
WHICH TYPE OF DATA CAN BE STORED
13
14. FORMAT SPECIFIER: A WAY TO TELL COMPILER WHAT
TYPE OF DATA IS GIVEN DURING INPUT OR OUTPUT
DATA TYPE FORMAT SPECIFIER TYPE
int %d
float %f
double %lf
char %c
14
15. VARIABLE: A VARIABLE IS A LOCATION
IN COMPUTER MEMORY
EX: int a=10
RULES FOR VARIABLE:
VARIABLE SHOULD NOT BE A RESERVED
WORD
SPECIAL SYMBOLS ARE NOT ALLOWED
1ST CHARACTER SHOULD BE ALPHABET
COMMA AND SPACES ARE NOT ALLOWED
LENGTH OF THE VARIABLE IS 31 CHARACTERS
15
16. STRUCTURE OF C
DOCUMENTATION SECTION
//--------------------
/*--------------------*/
LINKING SECTION----------->HEADER FILES
DEFINITION SECTION--->TO DECLARE
SYMBOLS
MAIN FUNCTION-------> LOGIC
16
TO GIVE COMMENTS
17. WORKING WITH C
TO WORK WITH C-Language WE NEED AN
EDITOR:
TURBO C 7
We need an editor to type, save, open,
compile & to run a program
17
Double click this icon
on desktop
19. #INCLUDE<STDIO.H>:
#--------> PREPOCESSOR
INCLUDE-----> INCLUDES THE FILES INTO PROGRAM
STDIO.H------> STDIO IS AN HEADER FILE THAT CONTAINS
FILES LIKE: INPUT & OUTPUT STATEMENTS.
EVERY C PROGRAM SHOULD HAVE ONE HEADER FILE.
MAIN(): EVERY C PROGRAM SHOULD HAVE ONE
MAIN(), THE PROGRAM EXECUTION STARTS FROM
MAIN().
19
20. AFTER WRITING THE PROGRAM WE HAVE TO
COMPILE THE PROGRAM TO CHECK ERRORS.
COMPILE------->
AFTER COMPILATION WE NEED TO RUN THE
PROGRAM FOR OUTPUT.
RUN---------->
20
ALT + F9
ALT + F5 CTRL + F9