The document discusses different data types in C including integer, real, character, and string. It describes integer types like decimal, octal, and hexadecimal, and how integers are represented on 16-bit computers. Real numbers can be decimal, exponential notation, float, or long double. Characters can be enclosed in single quotes and strings in double quotes. Variables are used to store and manipulate data and must be declared with a type before use. Variables can be initialized in their declaration.

2.  Integer
 Real
 Character
 String

3.  Decimal integer
◦ Consist of 0 through 9, +, -
 Octal integer
◦ Consist of 0 through 7, with a leading 0
 Hexadecimal integer
◦ Consist of 0 to 9, and a through f preceded by 0x or
0X

4.  The largest integer value is machine-dependent
 Qualifiers
◦ U or u: unsigned integer
◦ l or L: long integer
◦ UL or ul: unsigned long integer
◦ Short integer

5.  short is no longer than int and that long is no
shorter than int.

6.  Example2.1 Representation of integer constants on a 16-bit
computer.
#include<stdio.h>
main()
{
printf("Integer valuesnn");
printf("%d %d %dn",32767,32767+1,32767+10);
printf("n");
printf("Long integer valuesnn");
printf("%ld %ld %ldn",32767L,32767+1L, 32767+10L);
}

7.  (1) decimal point
◦ Consist of 0 through 9, . ,+ , -
◦ 3.14159, .94 , -.58 , +1.234
 (2)Exponential notation
mantissa e exponent
◦ .56e3 2.3e-3 -2.3E-3
◦ The exponent must be an integer number
 Suffixes f or F indicate a float constant
 L or l indicate a long double
 “Default values of constants” on page35

8.  Floating-Point Round-off Errors
 Take a number, add 1 to it, and subtract the
original number. What do you get? You get 1. A
floating-point calculation, may give another
answer:

9.  A character enclosed within ‘ ’
◦ ‘6’ ‘=‘ ‘;’ ‘ ‘
◦ Character constants have integer values, For example
◦ ‘a’ and 97
◦ ‘0’ and 48
 Backslash character constants
◦ Table2.5 on page28
◦ ‘ooo’ and ‘xhh’

10.  a sequence of characters enclosed in “ ”, for
example
◦ “hello” “34” “+()” “x” “n”
 “x” and ’x’

11.  A variable is data name that may be used to store
a data value.
◦ Variable names correspond to locations in the
computer's memory
◦ Every variable has a name, a type, a size and a value
◦ Whenever a new value is placed into a variable, it
replaces (and destroys) the previous value
◦ Reading variables from memory does not change them

12.  The declaration of variables must be done before
they are used.
 declaration form
data-type v1,v2,…,vn;
 for example
◦ int count;
◦ float sum;
◦ double ratio;
◦ char ch;

13.  To initialize a variable means to assign it a
starting, or initial, value.
 In C, this can be done as part of the declaration.
 char ch=‘ ’;
 int cows = 32,
 int dogs, cats = 94;