inicialComment

Author: lukas-bunat

1_introduction.cpp

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+//one line comment
+
+/*
+ *  Multi line comment
+ */
+
+/*
+ * Tips:
+ * 
+ * Do comment every functionally (especially functions) what are not 100 % clear what they do
+ * When you use any functionally from other sources (like stackoverflow) put the source into comment as reference
+ * Write clean code
+ * Always think about teh problem first, then start writting the code
+ * For help use offcial reference: en.cppreference.com
+ * Coding style: https://stackoverflow.com/questions/18170944/c-coding-style
+ * 
+ */ 
+
+//a library input
+//iostream library allows to manipuylate streams = allow to to print outputs and 
+#include <iostream>
+
+// see more on: https://www.tutorialspoint.com/cplusplus/cpp_namespaces.htm
+/*
+ * For now, most of the functions are store in std namespace
+ * To access them you have first access this namespace
+ * You access namespace by declarring is by std::
+ * By declaring at the beggining use don't have to declare every single function
+ */  
+using namespace std;
+
+/*
+ * main() is a function where program execution begins
+ * main has to return an int, therefore at the has be key word return followed by integer
+ */ 
+int main() {
+    // prints Hello World
+    cout << "Hello World"; 
+
+    //endl prints a new line
+    cout << endl;
+
+
+    /*
+     * data types in C++
+     * most of the types has unsigned type too
+     * numeric data types long type on top of that
+     */ 
+
+    //boolean
+    bool flag;
+    //character - 1B
+    char ch;
+    //integer - 4B
+    int i;
+    //floating point - 4B
+    float f;
+    //double floating point - 8B
+    double d;
+    //valueless is void - used mainly in fuctions
+
+
+    cout << "Enter a number" << endl;
+    //read standart input
+    cin >> i;
+
+
+    return 0;
+}

2_functions.cpp

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+#include <iostream>
+#include <string>
+
+using namespace std;
+
+int addNumbers( int a, int b = 50){
+    return a + b;
+}
+
+void overloadFunction(){
+    cout << "I am overload function with no argument" << endl;
+}
+
+void overloadFunction( int i ){
+    cout << "I am overload function with integer argument " << i << endl;
+}
+
+void overloadFunction( string str ){
+    cout << "I am overload function with string argument " << str << endl;
+}
+
+void overloadFunction( double d ){
+    cout << "I am overload function with double floating argument " << d << endl;
+}
+
+bool isPrime( int num ){
+
+    // Corner case 
+    if (num <= 1) 
+        return false; 
+  
+    // Check from 2 to n-1 
+    for (int i = 2; i < num; i++) 
+        if (num % i == 0) 
+            return false; 
+
+    return true;
+}
+
+
+//always devided your code into section by functionality - create functions
+int main (){
+
+    int num = 0;
+    cout << "Enter a number, you want to know if it is a prime number: ";
+    cin >> num;
+
+    cout << "The number " << num;
+    string myString = ( isPrime( num ) ) ? " is a prime number" : " is not a prime number";
+    cout << myString << endl;
+
+    //functions can be overloaded
+    //function with the same name but different arguments can do different task
+    overloadFunction();
+    overloadFunction( 5 );
+    overloadFunction( "test" );
+    overloadFunction( 5.55 );
+
+    //implicit arguments are "preset values" in function argument
+    //implicit arguments are used when no others are specified
+
+    cout << addNumbers( 10, 8 ) << endl;
+    //when second argument is ommited implicit is used
+    cout << addNumbers( 10 ) << endl;
+
+    return 0;
+}

3_references.cpp

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+#include <iostream>
+
+using namespace std;
+
+void hardSwap (int& first, int& second) 
+{ 
+    int temp = first; 
+    first = second; 
+    second = temp; 
+} 
+
+void swap2 (int *first, int *second) 
+{ 
+    int temp = *first; 
+    first = second; 
+    *second = temp; 
+} 
+
+void swap (int first, int second) 
+{ 
+    int temp = first; 
+    first = second; 
+    second = temp; 
+} 
+
+void pointerSwap (int *first, int *second) 
+{ 
+    int temp = *first; 
+    *first = *second; 
+    *second = temp; 
+} 
+
+
+int main(){
+
+    /*
+     * There are two types of references: (hard) reference & and pointer *
+     * Pointers "pointing" to a location (physical address) in memory where variable is store
+     * Reference is working directly with the variable on a specific address
+     * When passing varibale (not a reference) to a function a local copy is created for teh function
+     * To speed up your programs and work more efficiantly work with refrences and pointers
+     */
+
+    //declare local variable in main function
+    int x = 1, y = 2;
+    //create a general pointer
+    int *px;
+    //an address is assign a pointer
+    cout << px << endl;
+    //no value has been assigned yet
+    cout << *px << endl;
+    //assign a reference address to pointer
+    px = &x;
+    //the address has changed since the pointer is poiting to a different (new) variable
+    cout << px << endl;
+    //pointer is poiting to a value
+    cout << *px << endl;
+    //to access a value what pointer px is pointing to you have dereference a pointer
+    //to dereference a pointer add a * infront of pointer
+    *px = 3;
+    //address doesnt change
+    cout << px << endl;
+    //only the value was chnaged - the address stayed same
+    cout << *px << endl;
+
+    int &ry = y;
+    //to access value from a reference
+    ry = 4;
+    cout << ry << endl;
+
+
+    int x1 = 5;
+    int x2 = 10;
+
+    cout << "x1: " << x1 << endl;
+    cout << "x2: " << x2 << endl;
+
+    swap( x1, x2 );
+
+    cout << "x1: " << x1 << endl;
+    cout << "x2: " << x2 << endl;
+
+    hardSwap( x1, x2 );
+
+    cout << "x1: " << x1 << endl;
+    cout << "x2: " << x2 << endl;
+
+    pointerSwap( &x1, &x2 );
+
+    cout << "x1: " << x1 << endl;
+    cout << "x2: " << x2 << endl;
+
+    swap2 ( px, &x2 );
+
+    cout << "x1: " << x1 << endl;
+    cout << "x2: " << x2 << endl;
+
+
+    return 0;
+}

4_classes/4_classes.cpp

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+//in this main class are other classes only created and theirs methods are used
+//funtions stands alone whereas methods is a function inside a class 
+
+
+/*
+ * c++ program has 3 main parts: main.cpp, header file (.h) and class implementations in cpp
+ * Header file is a "link" between main file and class files 
+ * In header files are included class implementaions
+ * Main includes header files - therefore in main are header files an also class implementations
+ */
+
+//include header file of my class car
+#include "Car.h"
+
+int main(){
+
+    return 0;
+}

4_classes/Car.h

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+#include "Car.cpp"
+
+/*
+ * Implent my own class car
+ * Only heads of classes are showns here
+ * The only exception is one line function 
+ * 
+ * 
+ * 
+ */
+
+class Car{
+public:
+    //constructor
+    Car();
+    Car( int );
+    //copy cost
+    //op =
+    //destructor
+
+
+private:
+    
+
+}