03 helloworld in ‘c’
TRANSCRIPT
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Introduction to programming in C
Nihar Ranjan Roy
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History of C Programming language
The C programming language was designed by Dennis Ritchie at BellLaboratories in the early 1970s
In 1983 the American National Standards Institute (ANSI) began thestandardization process
In 1989 the International Standards Organisation (ISO) continued thestandardisation process
In 1990 a standard was finalised, known simply as Standard C Everything before this is known as K&R C Traditionally used for
systems programming.
Main source of documentation of K& R C The C Programming Language , by Brian Kernighan and Dennis Ritchie,
2nd Edition, Prentice Hall Referred to as K&R
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Characteristics of C Language
It recognizes the difference between lowercase and uppercase letters. It can be written with free format
Can write as many instructions as in a single line Its a structured programming language
During execution the control falls from the line at the top to the
Program consists of smaller units called functions.
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Building a C program#includeint main(void){...
}
Text Editor
Compiler 010010011110101
Programmer
Source Code
Object Code
___________ ________________ ________________ ________________
_
Linker
Loader
1110100001001.111010000111101 Executable
Code
Results
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Writing and editing programs Use any text editor (Ascii) available on your computer.
Example: windows (Edit,TC IDE,Notepad), Linux( Vi,Vim,emacs etc.) Compiling (windows)
With IDE ( Turbo C) Press Alt+F9
Command prompt ssue t e o ow ng comman tcc ename.c
Linking Running the program
Windows With IDE
Press CTRL+F9 Command Prompt
Issue the following command filename (hit enter) Linux
Issue the following command ./a.out or ./outputfilename ( hit enter)
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Structure of a C program
/* Preprocessor directives */
/* Global declarations */ #include int main(void)
int main(void){/*Local declarationsStatements*/}
/* other functions as required */
printf("Hello");return 0;
}
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My First C Program
#include /* comment */
int main(void)
tells compiler about stst anddard iinput and ooutput functions (i.e. printf + others)
main function
printf("Hello");return 0;
}begin
end
flag success
to operatingsystem
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Command Prompt(Windows) : Compiling & Running
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Turbo C IDE
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The Format of C
Statements are terminated withsemicolons
Indentation is ignored by the compiler. C is case sensitive - all keywords and
Standard Library functions are lowercase. Strin s are laced in double uotes
#include
/* comment */
int main(void){
rintf "Hello" Newlines are handled via \n
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return 0;}
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Problem
Write a program in C which asks the user what is your name?. Acceptsusers name and greets him as Hello,xxxx where xxxx is the name ofthe user.
What is your name?
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N arHello, Nihar
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2nd
Program
char name [30] ;declares a variable named name, which
can hold a string of up to 29characters (letter, digit, punctuation,etc.).
#includevoid main(){
printf ("What's your name? ");
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read your name into the variable name.
scanf("%s",name);printf("Hello, %s\n",name);}
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Problem
Write a program which accepts two integer numbers and displays itssum.
Enter two numbers:6 7The sum is 13
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3rd
Program
#includevoid main (){int a,b,sum;
We have made five changes to theoriginal program. We have
1. replaced the line defining name with onedefining other variables (a, b, and sum, alintegers)
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pr n n er wo num ers: ;scanf("%d %d",&a,&b);sum = a + b;printf("The sum is %d \n",sum);}
. c ange t e message n t e pr ntstatement
3. changed the format string and variablelist in the scanf statement
4. added the assignment statement sum = ab;
5. changed the format string and argumentlist in the final printf statement
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Conclusion & Queries
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