This document provides an overview of programming in C, including: 1) The objectives are to learn about the benefits and features of C, data types in C, C functions, input-output functions, and constructs in C. 2) C was developed from the B programming language by Dennis Ritchie and combines low-level capabilities of second-generation languages with high-level features like loops from third-generation languages. 3) C offers modular programming through block-structured functions that can be used as building blocks for more advanced functions.

1. Programming in C
Objectives
In this session, you will learn to:
Identify the benefits and features of C language
Use the data types available in C language
Identify the structure of C functions
Use input-output functions
Use constructs
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2. Programming in C
Identifying the Benefits and Features of C Language
Ken Thompson developed a new language called B.
B language was interpreter-based, hence it was slow.
Dennis Ritchie modified B language and made it a
compiler-based language.
The modified compiler-based B language is named as C.
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3. Programming in C
C as a Second and Third Generation Language
C language:
Possesses powerful low-level features of second generation
languages.
Provides loops and constructs available in third generation
languages.
Is very powerful and flexible.
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4. Programming in C
Block Structured Language - An Advantage for Modular Programming
C language:
Offers all essentials of structured programming.
Has functions that work along with other user-developed
functions and can be used as building blocks for advanced
functions.
Offers only a handful of functions, which form the core of the
language.
Has rest of the functions available in libraries. These functions
are developed using the core functions.
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5. Programming in C
Features of the C Language
The features that make C a widely-used language are:
Pointers: Allows reference to a memory location by a name.
Memory Allocation: Allows static as well as dynamic memory
allocation.
Recursion: Is a process in which a functions calls itself.
Bit Manipulation: Allows manipulation of data in its lowest form
of storage.
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6. Programming in C
Using the Data Types Available in C language
The types of data structures provided by C can be classified
under the following categories:
Fundamental data types
Derived data types
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7. Programming in C
Fundamental Data Types
Fundamental Data Types:
Are the data types at the lowest level.
Are used for actual data representation in the memory.
Are the base for other data types.
Have machine dependent storage requirement.
Are of the following three types:
char
int
float
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8. Programming in C
Fundamental Data Types (Contd.)
The storage requirement for fundamental data types can be
represented with the help of the following table.
Data Number of bytes on a Minimum Maximum
32-byte machine
char 1 -128 127
int 4 -2^31 (2^31) - 1
float 4 6 digits of precision 6 digits of precision
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9. Programming in C
Derived Data Types
Derived Data Types:
Are represented in memory as fundamental data type.
Some derived data types are:
– short int
– long int
– double float
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10. Programming in C
Derived Data Types (Contd.)
The storage requirement for derived data types can be
represented with the help of the following table.
Data Number of bytes Minimum Maximum
on a 32-byte
machine
short int 2 -2^15 (2^15) - 1
long int 4 -2^31 (2^31) - 1
double float 8 12 digits of precision 6 digits of
precision
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11. Programming in C
Defining Data
The syntax for defining data is:
[data type] [variable name],...;
Declaration is done in the beginning of a function.
Definition for various data types is shown in the following
table.
Data definition Data type Memory defined Size (bytes) Value assigned
char a, c; char a 1 -
c 1 -
char a = 'Z'; char a 1 Z
int count; int count 4 -
int a, count =10; int a 4 -
count 4 10
float fnum; float fnum 4 -
float fnum1, float fnum1 4 -
fnum2 = 93.63; fnum2 4 93.63
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12. Programming in C
Practice: 1.1
Write the appropriate definitions for defining the following
variables:
– num to store integers.
– chr to store a character and assign the character Z to it.
– num to store a number and assign the value 8.93 to it.
– i, j to store integers and assign the value 0 to j.
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13. Programming in C
Practice: 1.1 (Contd.)
Solution:
1. int num;
2. char chr=’Z’;
3. float num = 8.93;
4. int i, j=0;
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14. Programming in C
Defining Data (Contd.)
Defining Strings:
Syntax:
char (variable) [(number of bytes)];
Here number of bytes is one more than the number of
characters to store.
– To define a memory location of 10 bytes or to store 9 valid
characters, the string will be defined as follows:
char string [10];
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15. Programming in C
Practice: 1.2
Write the appropriate definitions for defining the following
strings:
– addrs to store 30 characters.
– head to store 14 characters.
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16. Programming in C
Practice: 1.2 (Contd.)
Solution:
1. char addrs[31];
2. char head[15];
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17. Programming in C
Identifying the Structure of C Functions
In C language, the functions can be categorized in the
following categories:
Single-level functions
Multiple-level functions
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18. Programming in C
Single Level Functions
Single Level Functions:
Consider the following single-level function:
main()
{
/*print a message*/
printf("Welcome to C");
}
In the preceding function:
– main(): Is the first function to be executed.
– (): Are used for passing parameters to a function.
– {}: Are used to mark the beginning and end of a function. These
are mandatory in all functions.
– /* */: Is used for documenting various parts of a function.
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19. Programming in C
Single Level Functions (Contd.)
– Semicolon (;): Is used for marking the end of an executable
line.
– printf(): Is a C function for printing (displaying) constant or
variable data.
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20. Programming in C
Practice: 1.3
Identify any erroneous or missing component(s) in the
following functions:
1. man()
{
printf("This function seems to be okay")
}
2. man()
{
/*print a line*/
printf("This function is perfect“;
}
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21. Programming in C
Practice: 1.3 (Contd.)
3. main()
}
printf("This has got to be right");
{
4. main()
{
This is a perfect comment line
printf("Is it okay?");
}
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22. Programming in C
Practice: 1.3 (Contd.)
Solution:
1. man instead of main() and semi-colon missing at the end of
the printf() function.
2. mam instead of main() and ‘)’ missing at the end of the
printf() function.
3. ‘}’ instead of ‘{‘ for marking the beginning of the function and
‘{’ instead of ‘}‘ for marking the end of the function.
4. Comment line should be enclose between /* and */.
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23. Programming in C
Multiple Level Functions
The following example shows functions at multiple
levels - one being called by another:
main ()
{
/* print a message */
printf ("Welcome to C.");
disp_msg ();
printf ("for good learning");
}
disp_msg ()
{
/* print another message */
printf ("All the best");
}
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24. Programming in C
Multiple Level Functions (Contd.)
The output of the preceding program is:
Welcome to C. All the best for good learning.
In the preceding program:
– main(): Is the first function to be executed.
– disp_msg(): Is a programmer-defined function that can be
independently called by any other function.
– (): Are used for passing values to functions, depending on
whether the receiving function is expecting any parameter.
– Semicolon (;): Is used to terminate executable lines.
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25. Programming in C
Practice: 1.4
Identify any erroneous or missing component(s) in the
following functions:
a. print_msg()
{ main();
printf(“bye”);
}
main()
{ printf(“This is the main function”);}
b. main()
{ /*call another function*/
dis_error();
}
disp_err();
{ printf(“Error in function”);}
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26. Programming in C
Practice: 1.4 (Contd.)
Solution:
a. main() is always the first function to be executed. Further
execution of the program depends on functions invoked from
main(). Here, after executing printf(), the program
terminates as no other function is invoked. The function
print_msg is not invoked, hence it is not executed.
b. The two functions, dis_error() and disp_error, are not
the same because the function names are different.
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27. Programming in C
Using the Input-Output Functions
The C environment and the input and output operations are
shown in the following figure.
Standard Input Device (stdin) Standard Output Device (stdout)
C Environment
Standard Error Device (stderr)
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28. Programming in C
Using the Input-Output Functions (Contd.)
These are assumed to be always linked to the C
environment:
stdin - refers to keyboard
stdin - refers to keyboard
stdout - refers to VDU
stderr - refers to VDU
Input and output takes place as a stream of characters.
Each device is linked to a buffer through which the flow of
characters takes place.
After an input operation from the standard input device, care
must be taken to clear input buffer.
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29. Programming in C
Character-Based Input-Output Functions
Character-Based Input-Output Functions are:
getc()
putc()
getchar()
putchar()
• The following example uses the getc() and putc()
functions:
# include < stdio.h>
/* function to accept and display a character*/
main ()
{char alph;
alph = getc (stdin); /* accept a character */
fflush (stdin); /* clear the stdin buffer*/
putc (alph, stdout); /* display a character*/
}
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30. Programming in C
Character-Based Input-Output Functions (Contd.)
• The following example uses the getchar() and
putchar() functions:
# include < stdio.h >
/* function to input and display a character using the
function getchar() */
main () {
char c;
c = getchar ();
fflush (stdin); /* clear the buffer */
putchar (c);
}
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31. Programming in C
Practice: 1.5
1. Write a function to input a character and display the
character input twice.
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32. Programming in C
Practice: 1.5 (Contd.)
Solution:
Microsoft Word
Document
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33. Programming in C
Practice: 1.6
• Write a function to accept and store two characters in
different memory locations, and to display them one after
the other using the functions getchar() and
putchar().
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34. Programming in C
Practice: 1.6 (Contd.)
Solution:
/* function to accept and display two characters*/
#include<stdio.h>
main()
{
char a, b;
a=getchar();
fflush(stdin);
b=getchar();
fflush(stdin);
putchar(a);
putchar(b);
}
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35. Programming in C
String-Based Input-Output Functions
String-based input-output functions are:
gets()
puts()
• The following example uses the gets() and puts()
functions:
# include < stdio.h >
/* function to accept and displaying */
main ()
{ char in_str {21}; /* display prompt */
puts ("Enter a String of max 20 characters");
gets (in_str); /* accept string */
fflush (stdin); /* clear the buffer */
puts (in_str); /* display input string */
}
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36. Programming in C
Practice: 1.7
1. Write a function that prompts for and accepts a name with a
maximum of 25 characters, and displays the following
message.
Hello. How are you?
(name)
2. Write a function that prompts for a name (up to 20
characters) and address (up to 30 characters) and accepts
them one at a time. Finally, the name and address are
displayed in the following way.
Your name is:
(name)
Your address is:
(address)
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37. Programming in C
Practice: 1.7 (Contd.)
Solution:
Microsoft Word
Document
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38. Programming in C
Using Constructs
There are two types of constructs in C language:
Conditional constructs
Loop constructs
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39. Programming in C
Conditional Constructs
Conditional Constructs:
Requires relation operators as in other programming language
with a slight change in symbols used for relational operators.
The two types of conditional constructs in C are:
• if..else construct
• switch…case construct
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40. Programming in C
Conditional Constructs (Contd.)
– The Syntax of the if..else construct is as follows:
if (condition)
{
statement 1 ;
statement 2 ;
:
}
else
{
statement 1 ;
statement 2 ;
:
}
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41. Programming in C
Practice: 1.8
1. Write a function that accepts one-character grade code, and
depending on what grade is input, display the HRA
percentage according to the following table.
Grade HRA %
A 45%
B 40%
C 30%
D 25%
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42. Programming in C
Practice: 1.8 (Contd.)
Identify errors, if any, in the following function:
#include<stdio.h>
/*function to check if y or n is input*/
main()
{
char yn;
puts("Enter y or n for yes/no");
yn = getchar();
fflush(stdin);
if(yn=’y’)
puts("You entered y");
else if(yn=‘n')
puts("You entered n");
else
puts("Invalid input");
}
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43. Programming in C
Practice: 1.8 (Contd.)
Solution:
Microsoft Word
Document
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44. Programming in C
Conditional Constructs (Contd.)
• Syntax of switch…case construct:
switch (variable)
{
case 1 :
statement1 ;
break ;
case 2 :
statement 2 ;
:
:
break;
default :
statement
}
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45. Programming in C
Practice: 1.9
Write a function to display the following menu and accept a
choice number. If an invalid choice is entered then an
appropriate error message must be displayed, else the
choice number entered must be displayed.
Menu
1. Create a directory
2. Delete a directory
3. Show a directory
4. Exit
Your choice:
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46. Programming in C
Practice: 1.9 (Contd.)
Solution:
Microsoft Word
Document
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47. Programming in C
Loop Constructs
The two types of conditional constructs in C are:
– while loop construct.
– do..while construct.
– The while loop construct has the following syntax:
while (condition in true)
{
statement 1 ; loop
statement 2 ; body
}
Used to iterate a set of instructions (the loop body) as long as
the specified condition is true.
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48. Programming in C
Loop Constructs (Contd.)
– The do..while loop construct:
• The do..while loop is similar to the while loop, except that the
condition is checked after execution of the body.
• The do..while loop is executed at least once.
• The following figure shows the difference between the while loop
and the do...while loop.
while do while
False Execute
Evaluate Body of
Condition Loop
True
Execute False
Body of Evaluate
Loop Condition
True
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49. Programming in C
Practice: 1.10
1. Write a function to accept characters from the keyboard
until the character ‘!’ is input, and to display whether the
total number of non-vowel characters entered is more than,
less than, or equal to the total number of vowels entered.
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50. Programming in C
Practice: 1.10 (Contd.)
Solution:
Microsoft Word
Document
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51. Programming in C
Summary
In this session, you learned that:
C language was developed by Ken Thompson and Dennis
Ritchie.
C language combines the features of second and third
generation languages.
C language is a block structured language.
C language has various features that make it a widely-used
language. Some of the important features are:
Pointers
Memory Allocation
Recursion
Bit-manipulation
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52. Programming in C
Summary (Contd.)
The types of data structures provided by C can be classified
under the following categories:
• Fundamental data types: Include the data types, which are used
for actual data representation in the memory.
• Derived data types: Are based on fundamental data types.
Fundamental data types:
• char, int, and float
Some of the derived data types are:
• short int, long int, and double float
Definition of memory for any data, both fundamental and
derived data types, is done in the following format:
[data type] [variable name],...;
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53. Programming in C
Summary (Contd.)
In C language, the functions can be categorized in the
following categories:
• Single-level functions
• Multiple-level functions
– For standard input-output operations, the C environment uses
stdin, stdout, and stderr as references for accessing the
devices.
– There are two types of constructs in C language:
Conditional constructs
Loop constructs
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