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Basics
Basic syntax and functions from the C++ programming language.
Boilerplate
#include using namespace std; int main() { cout << "Welcome To CodeWithHarry"; return 0 ; }
cout <<
It prints output on the screen cout << "This is C++ Programming";
cin >>
It takes input from the user cin >> variable_name
Data types
The data type is the type of data
Character type
Typically a single octet(one byte). It is an integer type char variable_name;
Integer type
The most natural size of integer for the machine
int variable_name;
Float type
A single-precision floating-point value float variable_name;
Double type
A double-precision floating-point value double variable_name;
Void type
Represents the absence of the type void
Boolean type
bool
Escape Sequences
It is a sequence of characters starting with a backslash, and it doesn't represent itself when used inside string literal.
Alarm or Beep
It produces a beep sound \a
Backspace
It adds a backspace
?
Octal No.
It represents the value of an octal number \nnn
Hexadecimal No.
It represents the value of a hexadecimal number \xhh
Null
The null character is usually used to terminate a string \ 0
Comments
A comment is a code that is not executed by the compiler, and the programmer uses it to keep track of the code.
Single line comment
// It's a single line comment
Multi-line comment
/* It's a multi-line comment */
Strings
It is a collection of characters surrounded by double quotes
Declaring String
// Include the string library #include // String variable string variable1 = "Hello World";
append function
It is used to concatenate two strings string firstName = "Harry "; string lastName = "Bhai"; string fullName = firstName.append(lastName); cout << fullName;
length function
It returns the length of the string string variable1 = "CodeWithHarry"; cout << "The length of the string is: " << variable1.length();
Accessing and changing string characters
string variable1 = "Hello World"; variable1[ 1 ] = 'i'; cout << variable1;
Maths
C++ provides some built-in math functions that help the programmer to perform mathematical operations efficiently.
max function
It returns the larger value among the two
if (condition) { // This block of code will get executed, if the condition is True }
If-else Statement
if (condition) { // If condition is True then this block will get executed } else { // If condition is False then this block will get executed }
if else-if Statement
if (condition) { // Statements; } else if (condition){ // Statements; } else{ // Statements }
Ternary Operator
It is shorthand of an if-else statement. variable = (condition)? expressionTrue : expressionFalse;
Switch Case Statement
It allows a variable to be tested for equality against a list of values (cases). switch (expression) { case constant-expression: statement1; statement2;
break; case constant-expression: statement; break; ... default: statement; }
Iterative Statements
Iterative statements facilitate programmers to execute any block of code lines repeatedly and can be controlled as per conditions added by the programmer.
while Loop
It iterates the block of code as long as a specified condition is True while (/* condition /) { / code block to be executed */ }
do-while loop
It is an exit controlled loop. It is very similar to the while loop with one difference, i.e., the body of the do-while loop is executed at least once even if the condition is False do { /* code / } while (/ condition */);
for loop
It is used to iterate the statements or a part of the program several times. It is frequently used to traverse the data structures like the array and linked list. for (int i = 0 ; i < count; i++) { /* code */ }
return_type function_name(data_type parameter...){ //code to be executed }
Function Call
function_name(arguments);
Recursion
Recursion is when a function calls a copy of itself to work on a minor problem. And the function that calls itself is known as the Recursive function. void recurse() { ... .. ... recurse(); ... .. ... }
Object-Oriented Programming
It is a programming approach that primarily focuses on using objects and classes. The objects can be any real-world entities.
class
class Class_name { public: // Access specifier // fields // functions // blocks };
object
Class_name ObjectName;
Constructors
It is a special method that is called automatically as soon as the object is created. class className { // The class public: // Access specifier className() { // Constructor cout << "Code With Harry"; } }; int main() { className obj_name; return 0 ; }
Encapsulation
Data encapsulation is a mechanism of bundling the data, and the functions that use them and data abstraction is a mechanism of exposing only the interfaces and hiding the implementation details from the user. #include using namespace std; class ExampleEncap{ private: /* Since we have marked these data members private,
- any entity outside this class cannot access these
- data members directly, they have to use getter and
- setter functions. / int num; char ch; public: / Getter functions to get the value of data members.
- Since these functions are public, they can be accessed
- outside the class, thus provide the access to data members
- through them */ int getNum() const { return num; } char getCh() const { return ch;
Reading the file
It allows us to read the file line by line getline()
Opening a File
It opens a file in the C++ program void open(const char* file_name,ios::openmode mode);
OPEN MODES
in
Opens the file to read(default for ifstream) fs.open ("test.txt", std::fstream::in)
out
Opens the file to write(default for ofstream) fs.open ("test.txt", std::fstream::out)
binary
Opens the file in binary mode fs.open ("test.txt", std::fstream::binary)
app
Opens the file and appends all the outputs at the end fs.open ("test.txt", std::fstream::app)
ate
Opens the file and moves the control to the end of the file fs.open ("test.txt", std::fstream::ate)
trunc
Removes the data in the existing file fs.open ("test.txt", std::fstream::trunc)
nocreate
Opens the file only if it already exists fs.open ("test.txt", std::fstream::nocreate)
noreplace
Opens the file only if it does not already exist fs.open ("test.txt", std::fstream::noreplace)
Closing a file
It closes the file myfile.close()
Exception Handling
An exception is an unusual condition that results in an interruption in the flow of the program.
try and catch block
A basic try-catch block in python. When the try block throws an error, the control goes to the except block
