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Introduction
In C++ programming, when you write a program, you use variables to store various types of information, like numbers or strings. These variables reserve memory locations to hold these values. When you declare a variable, you must specify its data type, such as int for integers or string for text, to define the kind of data it will store. This ensures that only the specified type of data is stored in the variable, aligning with C++'s strict data type requirements.
In simpler terms, a data type in C++ tells a variable what kind of data it can store. Each data type uses a specific amount of memory, which varies depending on the type. When you define a variable in C++, the compiler automatically allocates the necessary memory based on the data type you’ve chosen for that variable.
What is a data type in C++?
In C++, a data type specifies the type of data that a variable can hold, such as integers, floating-point numbers, characters, and more. It determines the size and layout of the variable's memory, the range of values that can be stored within that memory, and the set of operations that can be applied to the variable.
Types of Data Types in C++
There are broadly three types of data types in C++: Primitive data type, Derived data type, User Defined data type. The programmer can choose the data type best suited to the requirements of the application because C++ provides a wide range of data types. The size and type of values that will be saved are specified by data types. Although C++ instructions are the same across all platforms, the storage representation and machine instructions used to modify each data type vary from one machine to the next.
Primitive Data Types in C++
Primitive data types are the data types that are built-in or are predefined data types and are directly available for the user to use. Various types of Primitive data types are
1. Integer
The int data type in C++ is used to store whole numbers without any decimal points. It is commonly used for counting, indexing, or any situation where whole numbers are required. It has a size of 4 bytes and a range from -2147483648 to 2147483647, making it suitable for a wide range of integer values.
Syntax
int variable_name;
Example
int number = 100;
2. Character
The char data type is used to store individual characters, letters, or ASCII values. It occupies 1 byte of memory and can store values in the range of -128 to 127 (signed) or 0 to 255 (unsigned). It's ideal for representing characters in strings, symbols, or control characters.
Syntax
char variable_name;
Example
char letter = 'A';
3. Boolean
The bool data type is used to store logical values, which are either true or false. It occupies 1 byte of memory. This data type is particularly useful in conditional statements where the program needs to make decisions based on logical conditions, such as flags or binary outcomes.
Syntax
bool variable_name;
Example
bool isValid = true;
4. Floating Point
The float data type is used to store single-precision decimal numbers. It occupies 4 bytes of memory and provides 7 decimal digits of precision. It is typically used when storing values that require fractions, such as measurements or scientific data. However, it has less precision compared to double precision types.
Syntax
float variable_name;
Example
float pi = 3.14f;
5. Double Floating Point
The double data type is used to store double-precision floating-point numbers, offering higher precision than float. It occupies 8 bytes of memory and provides 15 decimal digits of precision. This data type is ideal for applications requiring more accurate calculations, such as scientific computing or financial systems.
Syntax
double variable_name;
Example
double e = 2.718281828459045;
6. Void or Valueless
The void data type is used to indicate that a function does not return any value. It is commonly used in functions that perform operations without providing a result, such as printing to the console or modifying global variables. It helps structure programs by organizing functions and reducing unnecessary output.
The wchar_t data type is used to store wide characters, which are characters that require more than 1 byte for representation. It typically occupies 2 or 4 bytes depending on the system. It is used when handling international text and characters that exceed the standard ASCII range, such as Unicode characters.
Syntax
wchar_t variable_name;
Example
wchar_t letter = L'A';
You can also do a free certification of Basics of C++.
Derived Data Types in C++
These are those data types that are derived from the built-in or so-called primitive data types. Various types of Derived data types are:
1. Function
It is defined as a piece or block of code that is defined to perform a specific, well-defined task. Functions are usually defined to save the user from writing the same lines of codes again and again for the same input. Functions make the code organised and reduce redundant lines of code. A function can be called anywhere required that too any number of times.
Syntax: Function_Type Function_Name( Parameters )
Example
C++
C++
#include <iostream> using namespace std;
void greet() { cout << "Hello, World!" << endl; }
int main() { greet(); // Calling the function return 0; }
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It is defined as the collection of similar items stored at continuous memory locations. The idea of using an array is to represent many instances in one variable.
Syntax: DataType Array_Name( size_of_array );
Example
C++
C++
#include <iostream> using namespace std;
int main() { int numbers[5] = {1, 2, 3, 4, 5}; // Array of 5 integers cout << "First number: " << numbers[0] << endl; return 0; }
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Pointers refer to a variable that holds the address of another variable; like any other variable, they too have a data type. It allows programs to simulate call-by-reference as well as create and manipulate dynamic data structure.
Syntax: DataType *variable_name;
Example
C++
C++
#include <iostream> using namespace std;
int main() { int num = 10; int *ptr = # // Pointer to the variable 'num' cout << "Value of num: " << *ptr << endl; // Dereferencing the pointer return 0; }
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A reference variable is an alias, i.e., another name given to a variable that already exists. A reference variable gets attached to the memory location of the original variable, thereby allowing the user to access the contents of the variable by either the original variable name or the reference.
int main() { int num = 20; int& ref = num; // Reference to the variable 'num' cout << "Value of num through reference: " << ref << endl; ref = 30; // Modifying the original variable via reference cout << "New value of num: " << num << endl; return 0; }
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The data types that are defined by the user themselves are known derived data types or user-defined data types. Various types of User Defined data types are:
1. Class
It consists of data members and member functions, which can be accessed and used by creating an instance (object) of the class. A class is a kind of blueprint for an object. Classes are the building block for C++ that leads to Object-Oriented Programming. Classes are created using the “class” keyword.
Classes are the building blocks of object-oriented programming and are used to create objects by encapsulating data and behaviour. Developers provide a systematic blueprint for organizing and managing data in a more streamlined and modular manner by defining classes with the "class" keyword.
Syntax:
Class ClassName
{
Access Specifer // Can take any one of the three values
// Private, Protected, Protected
Data members // variables to be used
Member functions // Methods/Functions to access the data members
}; // a class always ends with a semicolon
2. Structure
A structure creates a data type that is a collection of variables of different data types grouped together under a single name/type. A structure is declared using the struct keyword.
Syntax: struct Structure_Name{ // variables of different data types };
This syntax defines a C++ structure named "Structure_Name" that can hold variables of various data types. Structures are used to group related data together in a single unit.
3. Union
In union, all the members which are defined share the same memory location, i.e., any change brought in one member of the union will be reflected in all other members.
Syntax: union Union_name{ // data members };
4. Enumeration
It is a user-defined data type whose main purpose is to make the program easy to read and maintain. It is basically used to assign meaning full names to integral constants. To define an enumeration, the keyword enum is used.
Datatype modifiers are used together with built-in data types to adjust the amount of data that a given data type may contain.
Data Type Modifiers are keywords in C++ that are used to change the properties of a data type's current properties. The types of datatype modifiers are as follows:
long
short
unsigned
signed
Let us look at each one's size and range with the help of a table.
Data Type
Size (in bytes)
Range
short int
2
-32,768 to 32,767
unsigned short int
2
0 to 65,535
unsigned int
4
0 to 4,294,967 ,295
int
4
-2,147,483,648 to 2,147,483,647
long int
4
-2,147,483,648 to 2,147,483,647
unsigned long int
8
0 to 4,294,967,295
long long int
8
-(2^63) to (2^63)-1
unsigned long long int
8
O to 18,446,744,073,709,551,615
signed char
1
-128 to 127
unsigned char
1
0 to 255
float
4
-
double
8
-
long double
12
-
wchar_t
2 or 4
1 wide character
Macro Constants
Name
Expresses
#define
Defines a macro constant, which is replaced with its value during the preprocessing phase.
PI
Commonly used to represent the value of π (3.14159...), useful in mathematical operations.
MAX_SIZE
Represents the maximum size for arrays, buffers, or other data structures in the program.
DEBUG_MODE
Used to enable or disable debug-specific code sections, often set to 1 for true or 0 for false.
MIN_VALUE
Defines the minimum value allowed in a particular context, like an array or a loop condition.
FILE_PATH
Stores a string constant representing a commonly used file path within the program.
CONSTANT_NAME
Represents the name of the macro constant, typically written in uppercase letters by convention.
VALUE
The actual value assigned to the macro constant, which can be a number, string, or expression
ERROR_CODE
Represents a return value indicating an error occurred during execution (typically a negative value).
C++ Program to Find the Limits of Data Types Using Macro Constants
C++
C++
#include <iostream> #include <climits> #include <float.h> using namespace std; int main() { cout << "The range of char is from " << CHAR_MIN << " to " << CHAR_MAX << endl; cout << "For signed char, the range is from " << SCHAR_MIN << " to " << SCHAR_MAX << endl; cout << "Unsigned char can range from " << 0 << " to " << UCHAR_MAX << endl; cout << "The range of an int is from " << INT_MIN << " to " << INT_MAX << endl; cout << "For unsigned int, the range goes from " << 0 << " to " << UINT_MAX << endl; cout << "The range of short int is from " << SHRT_MIN << " to " << SHRT_MAX << endl; cout << "For unsigned short int, the range is from " << 0 << " to " << USHRT_MAX << endl; cout << "The range of long int is from " << LONG_MIN << " to " << LONG_MAX << endl; cout << "For unsigned long int, the range goes from " << 0 << " to " << ULONG_MAX << endl; cout << "The range of float is from " << FLT_MIN << " to " << FLT_MAX << endl; cout << "The range of double is from " << DBL_MIN << " to " << DBL_MAX << endl; cout << "For long double, the range is from " << LDBL_MIN << " to " << LDBL_MAX << endl; return 0; }
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The range of char is from -128 to 127
For signed char, the range is from -128 to 127
Unsigned char can range from 0 to 255
The range of an int is from -2147483648 to 2147483647
For unsigned int, the range goes from 0 to 4294967295
The range of short int is from -32768 to 32767
For unsigned short int, the range is from 0 to 65535
The range of long int is from -2147483648 to 2147483647
For unsigned long int, the range goes from 0 to 4294967295
The range of float is from 1.17549e-38 to 3.40282e+38
The range of double is from 2.22507e-308 to 1.79769e+308
For long double, the range is from 3.3621e-4932 to 1.18973e+4932
Advantages of Data Types in C++
Data types allow you to choose the best type for the data, which helps save memory. For example, using an int for whole numbers and float for decimals ensures your program uses only as much memory as needed.
C++ ensures that you can’t accidentally mix up different types of data. For instance, trying to use a string in a mathematical calculation will cause an error, preventing mistakes in the code.
C++ checks the data type before running the program, making sure that each variable is used correctly. This reduces bugs and unexpected behaviors in the code.
Choosing the right data type makes your program run faster. For example, using a short integer instead of a long integer can speed up calculations and reduce memory usage.
Using the correct data type for a variable helps others easily understand the code. If you see int, you know it stores an integer, and if you see double, you know it stores a decimal number.
C++ allows you to create your own data types with structures and classes. This helps you design more complex programs that can model real-world things, making your code flexible and easy to manage.
Disadvantages of Data Types in C++
Some data types, like double or long long, can take up a lot of memory. If you use them when you don’t need to, it can slow down your program.
If you change the data type of a variable, you might lose information. For example, changing a double to an int can cut off decimal values, leading to inaccurate results.
Pointers and references can be tricky. If you make a mistake with them, like using a null pointer or forgetting to clean up memory, it can cause your program to crash.
C++ has a strong type system, which means the data type must be decided ahead of time. Unlike some other languages, you can’t change the type of a variable during the program, which can sometimes be limiting.
You must declare every variable with its type in C++, which can make the code longer. This can be a problem if you have many variables or need to write a lot of code.
If you work with very large numbers or huge datasets, using the wrong data type can cause errors. For example, a float can lose precision, and a long long might not be the best option for smaller numbers.
Frequently Asked Questions
What are data structure types in C++?
C++ supports various data structures, including arrays, linked lists, stacks, queues, trees, graphs, and hash tables, for efficient data organization.
What is the smallest data type in C++?
The char data type, which typically uses 1 byte of memory, is the smallest data type in C++, used to store characters.
How many types of variables are there in C++?
C++ has three main types of variables: local, global, and static, each with different scopes and lifetimes within a program.
What are the 3 data types in C++?
The 3 types of data types in C++ are Built-in, user-defined, and derived. Built-in data types in C++ are pre-defined data types, user-defined data types are defined by the user, and derived are derived from existing data types in C++.
Conclusion
The most important concept to understand before beginning the coding portion of the language is the Data type. The type of data that every variable could hold is known as the data type, and examples include character, float, and integer data types. Every language has a variety of data types, thus studying each type in depth can help us use them effectively and accurately.