This document discusses variables and data types in C++. It defines a variable as a portion of memory used to store a value. Variables need unique identifiers as names. Valid identifiers can include letters, digits, and underscores, but not spaces or punctuation. Common data types in C++ include char for characters, int for integers, float for floating-point numbers, and bool for Boolean values. Variables can be declared with a data type and optionally initialized with a value assigned at declaration.

1. VARIABLES AND DATA TYPES
IICT – Lab-8 IN C++

2. VARIABLE
• Portion of Memory to Store a Value.
• Each variable needs a unique name that distinguishes it from
others.
• Name of the variable should be a valid C++ Identifier.
a=5;
b=2;
In this, variable names are ‘a’ and ‘b’

3. VARIABLE
Memory
5
a=5;
a
Memory Location reserved
And named as “a”

4. IDENTIFIERS
• A valid identifier is a sequence of one or more letters, digits or
underscore “ _ “
• A valid identifier shall always begin with a letter or underscore “ _ “
• A valid identifier CAN’T contain Spaces, punctuation marks or any
other symbols.
• A valid identifier CAN’T start with a digit in any case.
• A valid identifier CAN’T be a Reserved Keyword of C++

5. RESERVED KEYWORDS
Following are reserved keywords of C++ and can’t be used as
identifiers.
alignas, alignof, and, and_eq, asm, auto, bitand, bitor, bool, break,
case, catch, char, char16_t, char32_t, class, compl, const, constexpr,
const_cast, continue, decltype, default, delete, do, double,
dynamic_cast, else, enum, explicit, export, extern, false, float, for,
friend, goto, if, inline, int, long, mutable, namespace, new, noexcept,
not, not_eq, nullptr, operator, or, or_eq, private, protected, public,
register, reinterpret_cast, return, short, signed, sizeof, static,
static_assert, static_cast, struct, switch, template, this, thread_local,
throw, true, try, typedef, typeid, typename, union, unsigned, using,
virtual, void, volatile, wchar_t, while, xor, xor_eq

6. ARE THESE VALID IDENTIFIERS?
1. A
2. result
3. temppp
4. 6B
5. B46_34a
6. a.jok
7. 0_klm
8. _7ab
9. aaaa
10._a_b_







X
X
X

7. Result result RESULT resulT
C++ is a Case-Sensitive Language
and so are its Identifiers.
IDENTIFIERS

8. DATA TYPES
• Character [ char ]
• Integer [ int ]
• Float [ float ]
• Boolean [ bool ]

9. DECLARATION OF VARIABLES
• Identifier for variable, followed by its data type.
int a;
float mynumber;
• To declare more than one variables of same type, separate their
identifiers with commas, in single statement.
int a,b,c; int a;
int b;
int c;
(It is exactly same as declaring variables like this)

10. INITIALIZATION OF VARIABLES
• Assigning a value to the variable from the moment it is declared.
int a=5; (value of a is 5)
float mynumber=2.5; (value of mynumber is 2.5)
int b; (value of b is undertermined)