![Digits=0-9
Alphabets=A, B¡.Z and a, b, c¡.z
Special symbols ` ? ¡°? $ %&*() _ - + = {} [] etc.
CTokens: The alphabets, digits and special digit when properly combined are
called variable, constants and Keyword.
Constant are the entity that do not change during the program execution.
Variable are the entity that change during the program execution.
KEYWORDS: Keywords are also called as reserved words because the
meanings of the keywords are predefined. We cannot use them as a name of
variable because if we do this we are trying to assign new meaning to the
keywords which is not allowed. In C language there is 32 keywords:
auto double int struct
break else long switch
case enum register typedef
char extern return union
const float short unsigned
continue for signed void
default goto sizeof volatile
Do if static while
STATEMENT: Collection of C tokens prepares a C statements. After a C
statement we use a terminator which is ;.
FORMAT OF C:
? Every statement in C language terminated with ?;?.
? C is a case sensitive language so all the keywords and standard library
function should be lower case.
? Strings are placed in double quotes.](https://image.slidesharecdn.com/lect1-130530043706-phpapp01/85/Lect-1-2-320.jpg)
Lect '1'
- 1. WHAT IS ¡®C¡¯ LANGUAGE? Language is a medium of interaction or communication. As we are talking about the computer language, so it is a computer language that communicates through the complier. Compiler performs the two major operation: 1. Debugging 2. Converter Debugging is for making our program bugs free so that our code can work effectively. Converter is for converting source code to object code because it we know that computer can only understand binary/machine code. So it converts source code to object code. C language is developed by Brian Kernighan and Dennis Ritchie in 1972 at AT&T Bell Labs of USA PURPOSE: C language is used for the software development. FEATURES: 1. System Program Language-C is the system programing language, almost every platforms use it UNIX, windows 3.1, Windows 95, NT. 2. Fast execution speed 3. Mobile devices, consumer devices like microwave ovens, washing machines etc. are getting smart and this smartness comes from an operating system and program embedded in these devices. These program not only have to run fast but also have to work in limited amount of memory. Such an critical programs are written in C language. 4. In 3D computer games where user navigated some objects. For navigating objects the speed of navigation should be fast. So to match the expectation of the player C language is used for this purpose. CHARACTER SET: as other language has their own character set like English has the character set of alphabets with the help of which we make words, sentence and paragraphs. Character set are defined as the building blocks. C language has its own character set:
- 2. Digits=0-9 Alphabets=A, B¡.Z and a, b, c¡.z Special symbols ` ? ¡°? $ %&*() _ - + = {} [] etc. CTokens: The alphabets, digits and special digit when properly combined are called variable, constants and Keyword. Constant are the entity that do not change during the program execution. Variable are the entity that change during the program execution. KEYWORDS: Keywords are also called as reserved words because the meanings of the keywords are predefined. We cannot use them as a name of variable because if we do this we are trying to assign new meaning to the keywords which is not allowed. In C language there is 32 keywords: auto double int struct break else long switch case enum register typedef char extern return union const float short unsigned continue for signed void default goto sizeof volatile Do if static while STATEMENT: Collection of C tokens prepares a C statements. After a C statement we use a terminator which is ;. FORMAT OF C: ? Every statement in C language terminated with ?;?. ? C is a case sensitive language so all the keywords and standard library function should be lower case. ? Strings are placed in double quotes.
- 3. ? New lines are handled via /n PROGRAM: Collection of C statement to perform a particular task is called as a program. . We use these Header Files in C. Header files are the files that store function related to different works to be performed. stdio.h-standard input output file in which function like printf,scanf,puts,gets etc. are present conio.h-console input output file in which function related to output are stored like getch,getchar,clrscr etc. #include<stdio.h> #include<conio.h> Where #include directive instruct the C pre-processor to find the header files IMPORTANT FUNCTIONS USED WHILE CREATING A ¡®C¡¯ PROGRAM main()- it is the most important part of your program, it defines the point at which your program start executing. In main() you enter your coding. If you do not write any main function you program will never execute. clrscr ()- it clears the previous output from the output window. getch()-it retains the output screen unit you press any key. printf: function produces output on the screen. The sequence %.. instruct the printf to write on the screen scanf: scanf function is the opposite of the printf function. scanf reads from keyboard. The sequence %.. instruct the scanf to read from keyboard. The most important thing with the scanf is the use of & because it allow the program to change the value of the variable. We need not to use & sign with printf because after executing the statement the value of any variable will be automatically assigned to that variable.
- 4. A simple Program in C #include<stdio.h> #include<conio.h> void main() { clrscr();//for clearing all the previous output printf(¡°WELCOME IN C LANGUAGE¡±);//prints the msg getch();//retains the output screen } COMPILATION AND EXECUTION 1. Start the compiler at C> prompt. 2. Select New from the file menu 3. Type the program 4. Save the program using F2 or by using the file menu 5. Ctrl+F9 is used for compile and execute the program 6. Alt+F5 to view the previous output. ESCAPE CHARACTERS IN C n-New Line t-for tab space ¡±- for double quotes ¡¯-for single quotes -for slash symbol b-back space