C++ Data Types

Data Type is used to specify the proper use of identifier, which kinds of operands can be performed and what type of data can be stored within a variable.

System allocates some memory based on the data type specified by the programmer. It also specifies the type of data which is stored in the reserved memory.

Numeric Data Types:

Integers (whole numbers): 

· Used as: int (int a=19;)

· It used non-fractional numbers which can be positive or may be negative.

· Example: -78, 58

Types of Integer modifiers:

Floating Point (Decimal):

· Used as: float (double a=1.09;)

· Example: 3.14, - 6.53

Types of Floating Point modifiers:

Alphanumeric data Types:

Strings:

· It is part of Standard library; thus we need to include it in header as #include <string>.

· But as it already included with <iostream>, so you don’t need to include it separately.

· Composed of numbers, characters and symbols.

· Ordered sequence of characters.

· Literals are placed in between double quotation.

· Example: “Hello”, “We all are equal”

#include <iostream>

using namespace std;

int main(){

string a="king";  // string variable initialized

if(a=="king" || a=="Duke"){ // two condition based on string variable

cout<<"Yes, it is true"<<endl; // Executed: if any one of the condition will matched

   }

}

Characters:

· Used as: char (char x=’R’;)

· Composed of single letter or symbols.

· It holds a 1-byte integer which is interpreted in ASCII (American Standard Code for Information interchange) instead of integer.

· Literals enclosed between single quote.

· Example: ‘x’, ‘a’

Booleans Data Type:

·

· Used as: bool (bool age=true;)

· It only returns two possible values.

· Either True which means 1 or False which signifies 0.

Naming Conventions

· All variable must begin with a letter of the alphabet or an underscore.

· After the initial letter the variable name contains additional letter or numbers.

· Blank Spaces or Special character are not allowed.

· Variables are case sensitive in nature.

· C++ keywords cannot be used as variable names; those keywords are reserved for C++ use.


Camel case: The first letter of an identifier is lowercase and first letter of each subsequent word is capitalized. Example: mainActivity


Pascal case: Both the first letter of an identifier and first letter of each subsequent word are capitalized. Example: MainActivity