Is not required, but you may want to read "Learn To Love C" before read this material. You can find the C guide at http://github.com/jmarizgit/LTLC (in progress).
This is an online reference for C++. Written and maintaned by Mariz Melo.
You can find this documentation and the source files used here on the github repository at http://github.com/jmarizgit/LTLCPP.
Before we get start make sure to meet the requirements:
- A web browser (chrome, firefox, or safari);
- Familiarity with at least one programing language is recommended;
- An C++ compiler. You can compile and run all source code using http://compilr.com.
C++ (pronounced "see plus plus") is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features.[3] Developed by Bjarne Stroustrup starting in 1979 at Bell Labs, it adds object oriented features, such as classes, and other enhancements to the C programming language. Originally named C with Classes, the language was renamed C++ in 1983, as a pun involving the increment operator.
link: http://en.wikipedia.org/wiki/C%2B%2B
Here is how you write a simple hello world program in c++:
###hello.cpp
The "#include" (preprocessor) on top of our program says that the compiler should look for the standard library and include its content before proceed with the program compilation. This process is called "Preprocessor Directives".
The iostream library provides input and output functions to your program.
All programs in C/C++ must have one unique function called main(). This function is the start point of your program.
//Standard Libraries
#include <iostream> //input/output library
//main is an obrigatory function for c++ programs
int main()
{
std::cout << "Hello World!"; //using insertion operator (<<) to output message
return 0; // 0 = successfully exit
}###comments The " // " character is used at the beginning of the line and indicates a single line comment. The structure / comments / allows you to write comments using multiple lines.
// this is a single line comment
/* now I can comment using
multiple lines.
*/###datatypes.cpp
#include <iostream>
int main(){
char character; //1byte signed: -128 to 127, unsigned: 0 to 255
short shortint; //2bytes signed: -32768 to 32767, unsigned: 0 to 65535
int integer; //4bytes signed: -2147483648 to 2147483647, unsigned: 0 to 4294967295
long longint; //4bytes signed: -2147483648 to 2147483647, unsigned: 0 to 4294967295
double longdouble; //8bytes +/- 1.7e +/- 308 (~15 digits)
bool truefalse; //1byte true or false
return 0;
}###namespaces.cpp Namespaces are used to create "shortcuts" for objects, classes, and functions. The scope operator "::" grants you access to object variables and methods.
#include <iostream>
//example of namespace
namespace mariz{
int age = 31;
}
namespace samira{
int age = 25;
}
int main(){
//accessing namespace variables using the scope operator "::"
std::cout << mariz::age << endl;
std::cout << samira::age << endl;
return 0;
}###namespace_std.cpp Since input and output operations are very common in c++ programs is a good idea to have this namespace declaration in your programs. In fact I will be using this declaration for now on.
#include <iostream>
using namespace std; //"using" makes the namespace "std" available for the entire program
int main(){
//std::cout << "Hello World!"; //without "using" namespace "std"
cout << "Hello World!"; //we don't need the scope operator "::" because we are "using" namespace "std" globally
return 0;
}###input_output.cpp We will be using cin and cout. With "cout" we send messages to the standard output (in our case the monitor). With "cin" we read from the standard input (in this case the keyboard).
#include <iostream>
using namespace std;
int main(){
int number; //integer variable declaration
cout << "Enter a number:" << endl; //send message to the output
cin >> number; //reading input from user
cout << "you entered:" << endl;
cout << number; //displays entered number
}###functions.cpp
#include <iostream>
using namespace std;
//declaring a function
void hello(){
printf("Hello World!");
}
int main(){
hello(); //invoking our function
return 0;
}In our function below we are printing the string "Hello world!" to the default output.
void hello(){
printf("Hello World!");
}Here is how you invoke your function:
hello();###functions_parameters.cpp Parameters (or arguments) is how you can pass information to your functions. In our example above we send the "Hello world!" string using parameters.
#include <iostream>
using namespace std;
void hello(char message[]){
printf("%s", message);
}
int main(){
char msg[40] = "Hello World!"; //array of characters (chars)
hello(msg); //sending message using parameters
return 0;
}###functions_prototypes.cpp Note the instruction "void hello(char message[]);" on top of the program below. On the other hand our function is declared after our "main()" function. Declaring prototypes on top of our program will make the compiler "awere" of the function existence. Is a good way to organize your code. Programers just need to check on top of your program to see which functions can be used.
#include <iostream>
using namespace std;
//prototypes
void hello(char message[]);
int main(){
char msg[40] = "Hello World!"; //array of characters (chars)
hello(msg); //sending message using parameters
return 0;
}
void hello(char message[]){
printf("%s", message);
}The type "String" is an important part of any language, is not different in C++. Below you can have a brief idea how to use strings.
In GCC you don't need to insert the library "< string >" (in c++ you can omit the ".h" reference) if you already have "< iostream >" in your preprocessor directives.
We should not assume < iostream > being implemented always including < string >, so for security reasons include < string > in your preprocessor directives. This is an interesting discussion that you can read about here.
###strings.cpp
#include <iostream>
#include <string>
using namespace std;
int main(){
string s1 = "This"; //initializing a string
string s2, s3;
s2 = "Hello"; //assigning a string
s3 = ("World!"); //another way to assign
cout << s1+" "+s2+" "+s3 << endl;
return 0;
}###strings_comparasion.cpp The first thing to remember here is that C/C++ are case sensitive. That means that "hello" is not the same as "Hello" (capital letter on the first character). We will be using the method compare of strings.
#include <iostream>
#include <string>
using namespace std;
int main(){
//REMEMBER: C/C++ are case sensitive
string s1 = "Hello";
string s2 = "hello";
string s3 = "Hello";
//using built-in method "compare"
if ( s1.compare(s2) == 0 ){ // 0 indicates "equal"
cout << "s1 is EQUAL to s2" << endl; //comparing s1 and s2
}else{
cout << "s1 is NOT EQUAL to s2" <<endl;
}
if( s1.compare(s3) == 0 ){ //comparing s1 and s3
cout << "s1 is EQUAL to s3" << endl;
}else{
cout << "s1 is NOT EQUAL to s3" << endl;
}
return 0;
}File operations are very common in real-life applications. Implement this feature is easy in C++, different from C. You will need to include the "< fstream >" library using the preprocessor "#include".
###fstream.cpp
#include <iostream>
#include <fstream> //deal with files input/output
#include <string>
using namespace std;
int main(){
string buffer; //will hold temporarily content of file
ifstream in("lorem.txt"); //opening file "lorem.txt" for reading
while(getline(in, buffer)){
cout << buffer << "\n"; //reading line by line and send to monitor
}
}###lorem.txt
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Vivamus ultrices aliquet interdum.
In magna urna, cursus non volutpat ut, tincidunt et orci.
Cras lorem est, interdum euismod accumsan at, aliquam nec nisi.
Proin porttitor quam vitae massa fermentum condimentum.
Mauris eget condimentum justo.
Suspendisse potenti.
Donec blandit enim id turpis volutpat facilisis.
Suspendisse semper nisl sed nisl porta congue.
Aenean placerat risus eu ante volutpat ut volutpat nulla posuere.
Nunc tincidunt sapien vitae sapien gravida et faucibus metus lacinia.
Nunc a diam metus, rhoncus posuere purus.
C++ implements the OOP paradigm. Let's start with the concept of [classes](http://en.wikipedia.org/wiki/Class_(computer_science\)).
###classes.cpp
Classes are a way to group certain characteristics and behaviors of an object. With classes is easier for you to organize and upgrade your code.
ATTENTION: you must end the curl brackets with a semicolon (;) when declaring a class, otherwise you will get an error.
#include <iostream>
#include <string>
using namespace std;
//Your first class declaration
class Person{
string name;
int age;
}; //don't forget the semicolon when ending your class
int main(){
Person mariz; //creating an "instance" of Person
return 0;
}###access_specifiers.cpp
Private is the default access specifier in C++. Methods and attributes can only be accessed whithin the class.
Public attributes and methods can be accessed for the entire program.
Protected attributes and methods will act like private but can be accessed by inherited classes.
#include <iostream>
#include <string>
using namespace std;
class Person{
private: // ** optional ** all methods and attributes are private by default in c++
string email;
int age;
public: // will be accessible by the entire program
string name;
string language;
protected: //will be accessible by inherited classes
float height;
char size;
};
int main(){
Person mariz; //created an "instance" of Person
return 0;
}