Boilerplate Code
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}
cout <<
It is used to display output on screen.
cout << "Hello World!";
cin >>
It is used to get input from the user.
cin >> variable_name;
Data Types
Integer Data Type
It store the integer values
int variable_name;
Float Data Type
It store the decimal (point) values
float variable_name;
Double Data Type
It provide more precision then float
double variable_name;
Character Data Type
It store the single character
char variable_name;
Void Data Type
It show the absence of data type
void
Boolean Data Type
It represents true or false
bool
Escape Sequence
It is a sequence of characters that represent a special character. It cannot represent itself when it used inside a string. It start with a backslash(\n).
Newline
It is the Newline Escape Sequence.
cout<< "\n";
Tab
It is the tab Escape Sequence which give a tab space.
cout<< "\t";
Alarm or Beap
It triggers an alarm sound
cout<< "\ta";
Form feed
It is used to display output on screen.
cout<< "\f";
Backspace
It is used to add a backspace.
cout<< "\b";
Carriage return
It is used to display output on screen.
cout<< "\r";
Backslash
It is used to add a backslash.
cout<< "\\";
Single quote
It is used to add a single quotation mark.
cout<< "\";
Question Mark
It is used to add a question mark.
cout<< "\?";
Hexadecimal Number
It is used to represent hexadecimal number value.
cout<< "\xhh";
Octal Number
It is used to represent Octal number value.
cout<< "\nnn";
Null
It is used to terminate a string.
cout<< "\0";
Comments
Comment is that part of code that does not be compiled by compiler and does not display on screen.
Single Line Comment
// It is a single line comment.
Multi-Line Comment
/* It is a
Multi-Line
Comment
*/
Strings
It is a sequence of characters stored in memory
Declaring String
//First include the string library
#include <string>
//String Variable
string variable1 = "Hello World";
Append Function
It connects two strings
string first = "Hello ";
string last = "World";
string connect = first.append(last);
cout<< connect;
Accessing and Changing String Character
string variable2 = "Hello World"
variable2[3] = 'y';
cout<< variable2;
Length Function
It gives the length of the string
string variable3 = "Hello World";
cout<< "variable3.length()";
Maths
C++ contain some built in functions that helps programmers to do mathematical operations easily
Sqrt Function
It is used to get a square root of number given by programmer.
#include <math>
cout<< sqrt(169);
Max Function
It is used to get maximum of two values.
cout<< max(10, 20);
Min Function
It is used to get minimum of two values.
cout<< min(35, 45);
Pow Function
It is used to get the value of a to the power of b.
int x = pow(a, b);
Floor Function
It is used to get the value of a rounded down to its nearest integer.
double t = floor(3.06);
Ceil Function
It is used to get the value of a rounded up to its nearest integer.
double y = ceil(4.9);
Decision Making Statements
These statements are used to perform operations on the bases of conditions.
If statement
if (condition) {
// This block of statement will be execute if the condition is true.
}
If-Else Statement
if (condition) {
// Tis block of statement will execute if the condition is true.
} else{
// this block of statement will execute if the condition is false.
}
If Else-If Statement
if (condition) {
// Block of code can be executed if the the condition is true
}
else if {
// Block of code can be executed if the the condition1 is False
}
else {
// Block of code can be executed if the the condition1 and condition2 is False
}
Ternary Operator
It is the alternative of an if else statement.
variable = () ? True-Statement : False-Statement
Switch Statement
It is the alternative of an If Else-If Statement.
switch (expression)
{
case a:
// Block of statement
break;
case b:
// Block of statement
break;
...
default:
//Block of statement
}
Iterative Statements
These atatements are use to repeat the set of statements according to given condition.
While Loop
It display the set of statements till the condition is true
while (condition)
{
// Set of Statements
}
Do While Loop
It display the set of statements at least one time rather the condition false
do
{
// Set of Statements
} while(condition);
For Loop
In for loop you can Declare and Initalize variable with the condition and also Increment / Decrement
for(Initalization; Condition; Increment / Decrement;)
{
// Set of statements
}
Continue Statement
Continue is the keyword in C++. It skips the rest of the current iteration of loop and moves to the next iteration of the loop.
continue;
Break Statement
Break is a keyword in C++. It is used inside a loop and helps to terminate the loop.
break;
References
A reference is an alias in C++ for an existing variable. It allows coder to make a new name for a variable and enables indirect access without copying its value.
Creating Refferences
string variable1 = "V1"
string &variable2 = variable1
Pointer
A pointer is a variable in C++. It stores the memory address of another variable.
Declaration
datatype *variable_name;
variable_name = &variable2;
Functions & Recursion
Function is a program that divides the program into modules.
Function Defination
return_type function_name(data_type parameter...){
//Block of statement
}
Function Call
function_name(arguement);
Recursion
It is a coding method in which a function calls itself to solve a problem by dividing it into subproblems.
void recurse()
{
... .. ...
recurse();
... .. ...
}
OOP (Object Oriented Programming)
It is another method of writing code efficiently using classes and objects.
Class
class class_name {
public: // Access Specifier
// Fields
// Functions
// Blcoks
};
Object
class_name object_name
Constructor
A constructor is a special method in C++ that is automatically called when an object of a class is created.
class class_name { // The Class
public: // Access specifier
class_name() { //Constructor
cout<< "Hello World!";
}
};
int main() {
class_name obj_name;
return 0;
}
Encapsulation
It is a process that hides the internal details of a class and allows access through public methods to maintain security.
#include <iostream>
using namespace std;
class example_encap{
private:
int number;
char chrc;
int get_Numb() const {
return number;
}
chat get_Chr() const {
return chrc;
}
void set_Numb(int num) {
this->number = number;
}
void set_Chr(char chrc){
this->chrc = chrc;
}
};
int main () {
example_encap obj;
obj.set_Numb(80);
obj.set_Chr('B');
coutл< obj.get_Numb() <<endl;
coutл< obj.get_Chr() <<endl;
return 0;
}
File Handling
File handling means reading and writing data from Files. C offers many functions that help to manage data in files.
Creating & Writing to a Text File
#include <iostream>
#include <fstream>
using namespace std;
int main() {
// To create and open a text file
ofstream my_file("filename.txt");
// Write into the file
my_file << "Hello World!";
// Close the file
my_file.close(); }
Read the File
It is used to read a file.
getline()
Opening a File
It is use to open a file
void open(const char* file_name, ios::openmode mode);
In
It is used to open a file to Read.
fs.open ("file_name.txt, std::fstream::in")
Out
It is used to open a file to Write.
fs.open ("file_name.txt, std::fstream::out")
Binary
It is used to open a file in Binary mode.
fs.open ("file_name.txt, std::fstream::binary")
App
It is used to open a file and include all the outputs at the end.
fs.open ("file_name.txt, std::fstream::app")
Trunc
It is used to remove the data in the existing file.
fs.open ("file_name.txt, std::fstream::trunc")
Nocreate
It is used to open the file only if it already exists.
fs.open ("file_name.txt, std::fstream::nocreate")
Noreplace
It is used to open the file only if it does not already exist.
fs.open ("file_name.txt, std::fstream::noreplace")
Close a File
It is used to close a file.
my_file.close()
Exception Handling
It is a mechanism in C++ that handles RunTime Errors to prevent code crashes.
Try & Catch Block
They are used for exception handling to catch and handle RunTime Errors.
try {
// code for try
throw exception; // If problem occurs then throw an exception
}
catch () {
// Block of statement for errors handling
}
Leave a Comment