Hello world

We will learn through writing code. It is customary start with "Hello world!" program when learning a new programming language. This program simply prints a message in the terminal indicating the code ran successfully.

C

src/c/basics/00-hello-world.c

#include <stdio.h>

int main()
{
    printf("Hello C!\n");
    return 0;
}

C++

src/cpp/basics/00-hello-world.cpp

#include <iostream>
#include <cstdio> // original c standard io to use printf

int main()
{
    std::cout << "Hello C++!\n";
    // we can still use printf from c standard io
    printf("Hello from c standard io printf.\n");

    return 0;
}

Compile the code:

# in case of C
gcc filename.c

# in case of C++
g++ filename.cpp

It will produce an executable (binary) file named a.out. We can run the executable by typing:

./a.out

If you will to name your program something other than a.out, you can specify a custom name using -o flag:

gcc filename.c -o my_program

tip

1. It is possible to include entire standard library in C++ (it is a feature of g++ compiler) by:

#include <bits/stdc++.h>

2. Input and output streams can be made more efficient by including following in the beginning of the (main) program:

ios::sync_with_stdio(0);
cin.tie(0);

3. Use of newline \n is faster than endl, because endl always causes a flush operation.