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Basics of C++ Programming Language?
C++ is a programming language developed by Bjarne Stroustrup in 1979 at Bell Labs. C++ is regarded as a middle-level language, as it comprises a combination of both high-level and low-level language features. It is a superset of C, and that virtually any legal C program is a legal C++ program. C++ runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX.
It is a language that is −
- Statically typed − A programming language is said to use static typing when type checking is performed during compile-time as opposed to run-time.
- Compiled − A compiled language is a programming language whose implementations are typically compilers (translators that generate machine code from source code), and not interpreters (step-by-step executors of source code, where no pre-runtime translation takes place).
- General-purpose −A general-purpose language is a language that is broadly applicable across application domains, and lacks specialized features for a particular domain. This is in contrast to a domain-specific language (DSL), which is specialized to a particular application domain.
- Case-sensitive −C++ is case sensitive, ie, all identifiers, keywords, etc mean different things when they are in the different case.
- Free-form − A free-form language is a programming language in which the positioning of characters on the page in program text is insignificant.
- Procedural Programming − A procedural programming language is an imperative programming language whose programs have the ability to be primarily structured in terms of re-usable procedures, e.g. subroutines and/or functions.
- Object-oriented Programming −Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which may contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods.
- Generic Programming −Generic programming is a style of computer programming in which algorithms are written in terms of types to-be-specified-later that are then instantiated when needed for specific types provided as parameters.
So you've decided to learn how to program in C++ but don't know where to start. Here's a brief overview of how you can get started.
Get a C++ Compiler
This is the first step you'd want to do before starting learning to program in C++. There are good free C++ compilers available for all major OS platforms. Download one that suits your platform or you can use the tutorialspoint.com's online compiler on https://www.tutorialspoint.com/compile_cpp_online.php
- GCC − GCC is the GNU Compiler chain that is basically a collection of a bunch of different compilers created by GNU. You can download and install this compiler from http://gcc.gnu.org/
- Clang − Clang is a compiler collection released by the LLVM community. It is available on all platforms and you can download and find install instructions on http://clang.llvm.org/get_started.html
- Visual C++ 2017 Community − This is a free C++ compiler built for windows by Microsoft. You can download and install this compiler from https://www.visualstudio.com/vs/cplusplus/
Write a C++ program
Now that you have a compiler installed, its time to write a C++ program. Let's start with the epitome of programming example's, it, the Hello world program. We'll print hello world to the screen using C++ in this example. Create a new file called hello.cpp and write the following code to it −
Example
#include<iostream>
int main() {
std::cout << "Hello World\n";
}Let's dissect this program.
Line 1 − We start with the #include<iostream> line which essentially tells the compiler to copy the code from the iostream file(used for managing input and output streams) and paste it in our source file. Header iostream, that allows performing standard input and output operations, such as writing the output of this program (Hello World) to the screen. Lines beginning with a hash sign (#) are directives read and interpreted by what is known as the preprocessor.
Line 2 − A blank line: Blank lines have no effect on a program.
Line 3 − We then declare a function called main with the return type of int. main() is the entry point of our program. Whenever we run a C++ program, we start with the main function and begin execution from the first line within this function and keep executing each line till we reach the end. We start a block using the curly brace({) here. This marks the beginning of main's function definition, and the closing brace (}) at line 5, marks its end. All statements between these braces are the function's body that defines what happens when main is called.
Line 4 −
std::cout << "Hello World\n";
This line is a C++ statement. This statement has three parts: First, std::cout, which identifies the standard console output device. Second the insertion operator << which indicates that what follows is inserted into std::cout. Last, we have a sentence within quotes that we'd like printed to the screen. This will become more clear to you as we proceed in learning C++.
In short, we provide cout object with a string "Hello world\n" to be printed to the standard output device.
Note that the statement ends with a semicolon (;). This character marks the end of the statement
Compile the Program
Now that we've written the program, we need to translate it to a language that the processor understands, ie, in binary machine code. We do this using a compiler we installed in the first step. You need to open your terminal/cmd and navigate to the location of the hello.cpp file using the cd command. Assuming you installed the GCC, you can use the following command to compile the program −
$ g++ -o hello hello.cpp
This command means that you want the g++ compiler to create an output file, hello using the source file hello.cpp.
Run the program
Now that we've written our program and compiled it, time to run it! You can run the program using −
$ ./hello
Output
You will get the output −
Hello world
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