C++
What is C++?
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Compiled, general-purpose, free-form programming language.
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A middle-level language, as it comprises a combination of both high-level and low-level language features.
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Supports the object-oriented programming
History
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It was created in 1979.
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Developed by Bjarne Stroustrup at Bell Labs.
Why C++
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Very fast.
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Commonly used
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Extension version of C language.
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Object-oriented concept.
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Exception handling.
C++ Installation
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To run a C++ program we need a Text Editor & Compiler.
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Or an IDE (Text editor + Compiler + more).
Compiler
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Download C++ compiler.
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We installed GCC compiler from MinGW.
Set Environment Variable Path
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Set the bin folder of the compiler as Environment variable path.
Hello World
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We wrote the Hello World program in C++.
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But we build the environment for the Sublime Text editor for C++.
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By pressing Ctrl + B, we got the result.
Basic Syntax
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There is some base syntax we need to follow to write any C++ program.
Header file:
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At the beginning of the program, we need to include a header file.
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Here we use the iostream file, which provides input & output stream
Using namespace std:
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It tells the compiler to use a namespace/library which contains some function.
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If we did not mention using keyword, we can use the as follwing: std::cout << "Hello"
main():
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It is the main function, which holds the execution part.
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Return type is int.
cout():
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It is a function for print on console.
Comment line
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For single line comment: //
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For multiple line comment: /* */
Variable & Datatypes
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A variable holds a value, is the memory location by the compiler.
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Variables can be declared anywhere in the program in C++ but must be declared before they are used
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Each variable declaration has a datatype.
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Here below example shows some datatypes with declaration & initialization.
cin & cout
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std namespace has some console functions.
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cin >> used to take user input on a console.
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cout << used to print a string on a console.
Program 1
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Ask username & age, print a sentence with those variables.
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The output of the above program on the command prompt.
Compile .cpp file with gcc command
Run the exe file
Output
Class in C++
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A class provides the blueprints for objects.
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So basically an object is created from a class.
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The public data members of objects of a class can be accessed using the direct member access operator (.).
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A class definition starts with the keyword class.
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Here is an example of class:
File Handling
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In C++, we use fstream library for reading and writing a file.
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There are 3 datatypes for file:
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ofstream: For output file
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ifstream: For input file
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fstream: For both input and output
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Header files <iostream> and <fstream> must be included in your C++ source file.
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Functions for file functions are below:
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outfile.open("file.dat", ios::out | ios::trunc ); - For open a file
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void close(); - For close a file.
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<< - For write to file.
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>> - For read from file.
Write a File
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We use an ofstream or fstream object instead of the cout object.
Read a File
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We use ifstream or fstream object instead of the cin object.
Programs
Program 1
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Finding the first non-repeated character in String.
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Input: stonepfofits
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Output: n
Program 2
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Find the Permutation of string.
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Input: ab
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Output: ab, ba
Program 3
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Find Digit Identification if the string has any number.
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Input: Stone123Profits
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Output: True, if the string contains a number; False, if the string contains a number
Program 4
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Find and Replace the 1st highest repeated character with user given character.
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Input: abcabab
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Output: pbcpbpb
Program 5
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Write a program to print Diamond pattern.
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Input: 5
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Output: pattern
Program 6
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Write a program to sum the numbers in a string.
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Input: stone123profits7
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Output: 130
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Output on Command Prompt:
To Compile
To Execute
To Execute
User Input
Output