slide 03 - introduction to c
TRANSCRIPT
-
8/10/2019 Slide 03 - Introduction to C
1/18
Computer Science Department FTSM
Introduction to C
Knowledge:
Understand the complete structure of C programs in Linuxenvironment
Skill:Edit, compile and execute C programs
-
8/10/2019 Slide 03 - Introduction to C
2/18
TK1913-C Programming 2
Introduction /* Task: This program calculates BMI */#include #define WEIGHT 60.0#define HEIGHT 1.53
void main(void) {float bmi;
bmi = WEIGHT / (HEIGHT * HEIGHT);
if (bmi > 25.0)printf( \nYour BMI is %.2f. Need to lose weight! \ n, bmi);
}
Resembles AlgebraicExpression
Augmented by certainEnglish keywords
eg. if , else, while
C is a High-level LanguageCan also be used at lower-level
This flexibility allows it to beused for SYSTEMPROGRAMMING (eg.Operating systems likeUNIX and WINDOWS)
APPLICATIONPROGRAMMING
(Billing System,Sistem Semut ? )
C has small instruction set,though the actualimplementations include
extensive li brary functions
myfunction.h
C encourages usersto write additional
library
functions of their own
Finally, C programs are highlyportable.
They can be executed on differentplatforms without having to be
recompiled (or with little modification)
-
8/10/2019 Slide 03 - Introduction to C
3/18
-
8/10/2019 Slide 03 - Introduction to C
4/18
TK1913-C Programming 4
Editing C Program in Linux Use vi editor
$vi program_name.c
Use pico editor $pico program_name.c
Use emacs editor
$emacs program_name.c
Example: $pico myprogram.c
This is only an example ofprogram name. You can give
any name that you like.
-
8/10/2019 Slide 03 - Introduction to C
5/18
TK1913-C Programming 5
Compiling C Program in Linux To compile C GNU: $gcc program_name.c
An error message will be displayed if there isany syntax error Needs to be rectified until
there is no more errorsIf succeeded, the output will be generated intothe execution file, namely a.out
To display the output on the screen: $a.out
Example: $gcc myprogram.c$a.out
-
8/10/2019 Slide 03 - Introduction to C
6/18
TK1913-C Programming 6
Another method to compile C GNU:$gcc o file_name program_name.c
An error message will be displayed if there is anysyntax error Needs to be rectified until there isno more errors
If succeeded, the output will be generated intothe execution file, namely file_name
To display the output on the screen: $file_name
Compiling C Program in Linux
Example: $gcc output myprogram.c$output
This is only an example ofexecution file name. You can give
any name that you like.
-
8/10/2019 Slide 03 - Introduction to C
7/18
TK1913-C Programming 7
Don t WorryBe Happy Got confused?? Dont
worry, youll acquire thisskill during the labsession. Ensure you know
your lab group andschedulegood luck!
-
8/10/2019 Slide 03 - Introduction to C
8/18
TK1913-C Programming 8
History of C LanguageC was originated from 2 programming languages, namelyBCPL and B BCPL was developed by Martin Richards in year 1967. It
was intended as a language to develop operating systemsand compilersB was developed by Ken Thompson in year 1970s. It wasused to develop UNIX operating system at Bell
LaboratoriesC was developed by Dennis Ritchie in year 1972. Itreplaced B as the language to develop UNIX operatingsystem at Bell Laboratories
-
8/10/2019 Slide 03 - Introduction to C
9/18
TK1913-C Programming 9
C Program StructurePreprocessorInstruction
void main (void){
}
Statement
Global Declaration
Local Declaration
-
8/10/2019 Slide 03 - Introduction to C
10/18
TK1913-C Programming 10
Example of C Program
#include
void main(void) {
printf(Welcome to UKM!);
}
program
Main function
statementPreprocessor instruction
-
8/10/2019 Slide 03 - Introduction to C
11/18
TK1913-C Programming 11
Preprocess Instruction2 types of preprocess instruction that arenormally used:
#include
#define
#include is used to include certain files into the program. Those files need to be included
because they contain the necessary informationfor compilation (e.g. stdio.h file containsinformation about printf function)
-
8/10/2019 Slide 03 - Introduction to C
12/18
TK1913-C Programming 12
Preprocess Instruction#define is used to declare macro constants
Example:
#include #define PI 3.141593
void main(void) {
float luas;luas = PI * 7 * 7;printf(Luas %.2f:, luas);
}
Macro constant
Before preprocessExample:#include #define PI 3.141593
void main(void) {float luas;luas = 3.141593 * 7 * 7;printf(Luas %.2f:, luas);
}
After preprocess
-
8/10/2019 Slide 03 - Introduction to C
13/18
TK1913-C Programming 13
Main Function
Every C program must have a mainfunction, called main()
The execution of C program starts frommain() function
-
8/10/2019 Slide 03 - Introduction to C
14/18
TK1913-C Programming 14
StatementSentence -like action steps that are written in the
body of the functionIn C, all statements must be ended with ; symbol
Example: A statement to display a string ofcharacters on the screen by using printf() function
printf(Welcome to UKM);
Output:
Welcome to UKM
-
8/10/2019 Slide 03 - Introduction to C
15/18
TK1913-C Programming 15
CommentYou could include comments in your program to easeunderstanding
Comments will be ignored during compilation
A block of comment is labeled with /* (start) and */ (end) compiler will ignore any text written after /* symbol till */ symbol is found
Nested comments (comment within comment) are notallowed, for example:
/* my comment /* subcomment */ my comment continues */
-
8/10/2019 Slide 03 - Introduction to C
16/18
-
8/10/2019 Slide 03 - Introduction to C
17/18
TK1913-C Programming 17
Example of C Program
Welcome to
Fakulti Teknologi dan Sains Maklumat
What will the output be?
-
8/10/2019 Slide 03 - Introduction to C
18/18