C Programming-Lecture Notes-01-Overview of C.pdf

B.Bhuvaneswaran, AP (SG) / CSE
9791519152
bhuvaneswaran@rajalakshmi.edu.in
Programming Logic
Overview of C

Overview of C
Overview of C Rajalakshmi Engineering College 2
Rajalakshmi Engineering College 2
Basics of C Language
 C language was developed by Dennis Ritchie of Bell Laboratories in
New Jersey in the year 1972.
 The language was named as C because it was the successor of
another language called B.

Overview of C
Compilers Vs Interpreters
Compilers Interpreters
A compiler reads entire program
and converts it to the object
code.
An interpreter reads only one line
of source program at a time and
converts it to object code.
It provides errors not of a single
line but errors of the entire
program.
In case of any error, the same will
be indicated instantly.
It consumes little time for
converting a source program to
an object program.
It is more time-consuming for
converting a source program to
an object program.
Example: C Compiler Example: BASIC

Overview of C
Compilers Vs Interpreters

Overview of C
History of ANSI C

Overview of C
Procedure-oriented Programming
 C is commonly known as procedure-oriented programming (POP).
 In the procedure-oriented approach, the problem is viewed as a
sequence of things to be done such as reading, calculating and
printing.
 A number of functions are written to accomplish these tasks.
 The primary focus is on functions.
 The technique of hierarchical decomposition has been used to
specify the tasks to be completed for solving a problem.

Overview of C
Typical Structure of POP

Overview of C
Relationship of Data & Functions in POP

Overview of C
Features of C Language
C
Language
Portability
Modularity
Flexibility
Speed
Extensibility
Compactness
Case Sensitive

Overview of C
Basic Structure of C Programs

Overview of C
Documentation Section
 The documentation section consists of a set of comment lines
giving the name of the program, the author and other details,
which the programmer would like to use later.

Overview of C
Link Section
 The link section provides instructions to the compiler to link
functions from the system library.

Overview of C
Definition Section
 The definition section defines all symbolic constants.

Overview of C
Global Declaration Section
 There are some variables that are used In more than one function.
 Such variables are called global variables and are declared in the
global declaration section that is outside of all the functions.
 This section also declares all the user–defined functions.

Overview of C
main() function Section
 Every C program must have one main() function section.
 This section contains two parts:
• declaration part and
• executable part.

Overview of C
main() function Section
 The declaration part declares all the variables used in the
executable part.
 There is at least one statement in the executable part.
 These two parts must appear between the opening and the
closing braces.
 The program execution begins at the opening brace and ends at
the closing brace.
 The closing brace of the main function section is the logical end of
the program.
 All statements in the declaration and executable parts end with a
semicolon(;).

Overview of C
Sub program Section
 The subprogram section contains all the user–defined functions
that are called In the main function.
 User–defined functions are generally placed immediately after the
main function, although they may appear in any order.

Overview of C
Important Note
 All sections, except the main function section may be absent when
they are not required.

Overview of C
Executing a C Program
 Executing a program written in C involves a series of steps. These
are:
• Creating the program;
• Compiling the program;
• Linking the program with functions that are needed from the C library; and
• Executing the program.

Overview of C
Compiling and Running a C Program

Overview of C
Compilation of Multiple Files

Overview of C
Header Files
 A header file is a file with extension .h which contains C function
declarations and macro definitions to be shared between several
source files.
 There are two types of header files:
• the files that the programmer writes and
• the files that come with C compiler.
 The header file is linked to the code by:
• #include <stdio.h>

Overview of C
Header Files

Overview of C
stdio.h
 All formatted and unformatted functions include file operation
functions defined in this file.
 The most useful formatted printf() and scanf() are defined in this
file.
 Most useful functions from this header files are printf(), scanf(),
getchar(), gets(), putc() and putchar().

Overview of C
List of Header Files
alloc.h assert.h bcd.h bios.h complex.h
conio.h ctype.h dir.h dirent.h dos.h
errno.h fcntl.h float.h fstream.h generic.h
graphics.h io.h iomanip.h iostream.h limits.h
locale.h malloc.h math.h mem.h process.h
setjmp.h share.h signal.h stdarg.h stddef.h
stdio.h stdiostr.h stdlib.h stream.h string.h
strstrea.h sysstat.h systimeb.h systypes.h time.h
values.h

Overview of C
Comments
 Comments are used to document programs and improves
readability.
 In C a comment will start with /* and ends with */.
 The C Compilers ignores the comments.
 Compilers do not provide any machine language object code for
the comments.
 Syntax:
/* Comments */

Overview of C
Examples
/* This is a single line comment */
/* This is a multiline
* comment in C */
/******************************************************
* This style of commenting is used for functions
******************************************************/

Overview of C
Code Indentation
 Indentation is the practice by Software Engineers to use spaces or
tabs (4 spaces) consistently in every line of code to group lines
together based on their scope for easy readability.
 An indented code looks better and can be understood easily.

Overview of C
Algorithm
 Algorithm is an ordered sequence of finite, well defined,
unambiguous instructions for completing a task.
 Algorithm is an English-like representation of the logic which is
used to solve the problem.
 It is a step- by-step procedure for solving a task or a problem.
 The steps must be ordered, unambiguous and finite in number.

Overview of C
Algorithm-Greatest of 3 Nos.-Alg. -1
Step 1: Start
Step 2: Read the three numbers A, B, C
Step 3: Compare A and B. If A is greater perform step 4 else perform
step 5.
Step 4: Compare A and C. If A is greater, output “A is greatest” else
output “C is greatest”. Perform step 6.
Step 5: Compare B and C. If B is greater, output “B is greatest” else
output “C is greatest”.
Step 6: Stop

Overview of C
Algorithm-Greatest of 3 Nos.-Alg. -2
Step 1: Start
Step 2: Read the three numbers A, B, C
Step 3: Compare A and B. If A is greater, store A in MAX, else store B
in MAX.
Step 4: Compare MAX and C. If MAX is greater, output “MAX is
greatest” else output “C is greatest”.
Step 5: Stop

Overview of C
Flowchart
 A flowchart is a diagrammatic representation of the logic for
solving a task.
 A flowchart is drawn using boxes of different shapes with lines
connecting them to show the flow of control.
 The purpose of drawing a flowchart is to make the logic of the
program clearer in a visual form.

Overview of C
Flowchart Symbols

Overview of C
Pseudocode
 Pseudo code consists of short, readable and formally-styled
English language used for explaining an algorithm.
 Pseudo code does not include details like variable declarations,
subroutines etc.
 Pseudo code is a short-hand way of describing a computer
program.

Overview of C
Examples of Pseudocode

Overview of C
Online C/C++ Compilers
 https://ideone.com/
 http://codepad.org/
 https://www.codechef.com/ide
 https://www.jdoodle.com/c-online-compiler/
 https://www.onlinegdb.com/
 https://godbolt.org/

Overview of C
C/C++ IDEs
 https://www.eclipse.org/downloads/download.php?file=/technol
ogy/epp/downloads/release/2020-03/R/eclipse-cpp-2020-03-R-
incubation-win32-x86_64.zip
 https://www.fosshub.com/Code-Blocks.html?dwl=codeblocks-
20.03-setup.exe
 https://aka.ms/win32-x64-user-stable
 https://downloads.codelite.org/downloads.php?windows_weekly
_64
 https://www.apache.org/dyn/closer.cgi/netbeans/netbeans/11.3/
netbeans-11.3-bin.zip
 https://bloodshed-dev-c.en.softonic.com/support

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