C++ Introduction

C++ Overview

a cross platform language that is used to create high-preformance applications
created by Bjarne Stroustrup as an extension to the C language
C++ is designed to be a compiled language, meaning that it is generally translated into machine language that can be understood directly by the system, making the generated program highly efficient.
gives programmers a high level of control over system resources and memory.
an object-oriented language which gives a clear structure to programs and allows code to be reused, lowering development costs.
Close to C, C# and Java. it makes it easy to switch between them.

Features:

Modular structured-programming, can be divided into small modules(using functions)
Object-oriented programming
Memory management
Mid-level programming
Rich library

Phases and Steps in Programming

Software development methodology(SDM):

Problem specification, specifying the problem clearly and unambiguously
Analysis, consists of IOFC, IO format, and Variables
Design, cosists of Algorithm, Flowchart, Pseudocode, and control structures
Implementation, consists of coding, IDE
Testing, consists of unit testing + debugging + verification, test cases, execution, comparison
Documentation, consists of comments and files

C++ Get Started

C++ Fundamentals

Basic elements

Reserved words: These are keywords in the C++ language that have special meaning and cannot be used as identifiers. Examples of reserved words include “if”, “else”, “for”, “while”, and “class”.
Character: A character is a single letter, digit, or symbol in the C++ language. Characters are enclosed in single quotes (‘ ‘), such as ‘a’, ‘1’, or ‘#’.
Identifier: An identifier is a name given to a variable, function, or other program element in C++. Identifiers must start with a letter or underscore character, and can consist of letters, digits, and underscores.
Variable, constant: A variable is a named memory location that can hold a value. Variables in C++ must be declared with a data type, such as “int” or “double”, before they can be used. A constant is a fixed value that cannot be changed during program execution.
Literals: A literal is a value that is written directly into a program, such as a number or string. Examples of literals in C++ include 5 (an integer literal), 3.14 (a floating-point literal), and “hello” (a string literal).
Data types: C++ provides a variety of data types, including integers (such as “int” and “long”), floating-point numbers (such as “float” and “double”), characters (such as “char”), and Boolean values (such as “bool”). Data types determine the range of values that can be stored in a variable and the operations that can be performed on those values.

Data types

Peogramming operators

ARITHMETIC Expression:

to preform arithmetic operations on variables, computes a value of type int, float, or double
Binary operators(operation on 2 operands): +, -, *, /, %
Unary operators(operation on 1 operand): ++, –, +, -
Assignment operators: =, +=, -=, *=, /=, %=

RELATIONAL Expression:

to preform comparison operations on 2 operands, the result is a boolean value(true or false)
==, !=, >, <, >=, <=

LOGICAL Expression:

to preform complex comparison operations, the result is a boolean value(true or false)
&&, , !

CONDITIONAL Expression:

Works on 3 operands, used instead of if-else statements
?:
x = (a > b) ? a : b; // if a > b, x = a, else x = b

Precedence and associativity rules

Depend on IDE. Precedence and associativity rules

Data type casting

to cast one data type to another
to ensure that you do not lose any data from arithmetic operations

synatx: (type) expression e.g:

int a = 10;
float b = 3.14;
float c = (float) a + b; // c = 13.14, if used without casting(float), c = 13

Both endl and \n serve the same purpose in C++ – they insert a new line. However, the key difference between them is that endl causes a flushing of the output buffer every time it is called, whereas \n does not. Flushing of buffers is an Operating System task. Each time the buffer is flushed, a request has to be made to the OS and these requests are comparatively expensive. Furthermore, we don’t really need to flush the buffer every time we write something to the stream, since the buffers get flushed automatically when they get full. In the rare cases we do need to perform flushing, we can explicitly specify the operation using either cout.flush() or by inserting std::flush into the stream. Writing \n characters directly to the stream is more efficient since it doesn’t force a flush like std::endl.

C++ Flow Control

Control structures

Flow:

Sequence
Selection
Repetition

Selection/Conditional flow

Single-Alternative:

if (condition) {
    // statements
}

Double-Alternative:

if (condition) {
    // statements
} else {
    // statements
}

Multiple-Alternative:

if (condition) {
    // statements
} else if (condition) {
    // statements
} else {
    // statements
}

Repetition/Looping design

Counter controlled loop:

definite looping
Execute loop body statements for a, pre-determined number of time.
Loop depends on arithmetic or conditional expression.

Sentinel controlled loop:

indefinite looping
Execute loop body statements until the user tells it to stop or a special condition is met.
Loop depends on sentinel value.

Repetition/Looping types

Entry-checking loop:

Condition is checked before the first iteration of the loop.
The loop body is executed zero or more times.
while loop and for loop

Exit-checking loop:

Condition is checked after the body of the loop has been executed once.
The loop body is executed one or more times.
do-while loop

C++ Functions

a function is a block of code that performs a specific task.
can be written in one program and used by another program without rewriting the code.- promotes code reusability.
can be put in a library - to use them include the library in the program.
categorized into 2 types:
- Pre-defined functions: exist in the C++ library, e.g: cout << "Hello World";
- User-defined functions: written by the programmer, e.g: int add(int a, int b) { return a + b; }

Types of user-defined functions

No argument and no return value

void printHello() {
  cout << "Hello World";
}

No argument and return value

int add() {
  int a, b;
  cin >> a >> b;
  return a + b;
}

Argument and no return value

void printHello(string name) {
  cout << "Hello " << name;
}

Argument and return value

int add(int a, int b) {
  return a + b;
}

C++ Arrays

Numeric Arrays

an array is a consecutive memory locations of the same name for storing values of same data typeused for the exact same purpose.
arrays can be one-dimensional or multi-dimensional.
conceptually you can think of a 1D aray as a row where elements are stored one after another.
syntax: type name[size]; e.g: int arr[5];

Passing individual array elements to functions

Similar to passing variables to functions:

void print(int x) {
    cout << x;
}

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    for (int i = 0; i < 5; i++) {
        print(arr[i]);
    }
} // prints 12345

Passing arrays to functions

Only the name of the array is passed to the function as an argument, not the entire array.

void print(int arr[], int size) {
    for (int i = 0; i < size; i++) {
        cout << arr[i];
    }
}

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    print(arr, 5); // prints 12345
}

C++ Strings

What are strings?

String is a collection of characters.
two types of strings commonly used in C++:
1. C-style strings: A C-string is a special kind of 1D array of characters ending with the null character (‘\0’).
```
  char str[6] = {'H', 'e', 'l', 'l', 'o', '\0'};
```
2. C++ strings: has NO fixed length, and can be extended as per your requirement.
```
  string str = "Hello";
```

String input and manipulation functions

iostream:

getline(cin, str); to get a string with spaces.

cstring:

strlen(str); to get the length of a string.
strcpy(str1, str2); to copy a string. strncpy(str1, str2, n); to copy n characters.
strcat(str1, str2); to concatenate two strings. strncat(str1, str2, n); to concatenate n characters.
strcmp(str1, str2); to compare two strings. strncmp(str1, str2, n); to compare n characters.

Passing strings to functions

Strings are passed to a function in a similar way arrays are passed to a function.

void print(string str) {
    cout << str;
}

int main() {
    string str = "Hello";
    print(str); // prints Hello
}

Notes

reference notes