basics

all c++ programs must have a main() function

Comments

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Initialization

double d = 1.7789856453427678;
int a{d}; //Compile time error - value of d will not fit in a
int a(d); //ok - a is 1
int a = d; //ok - a is 1

Why so many ways of initialization?

It is an historical question. The first one is int i=0;. This one is from the early C language from the 1970's.

Next first C++ versions introduced a function like initialization syntax which writes here int i(0);.

But because of the most vexing parse ambiguities, the curly braces initialization was invented.

And for compatibility reasons, all those syntaxes are still valid...

https://stackoverflow.com/questions/62756177/why-have-different-ways-of-variable-initialization-in-c

Printing

std::cout

<< is a insertion operator

#include <iostream> // for std::cout

int main()
{
    int x{ 5 };
    std::cout << "x is equal to: " << x;
    return 0;
}

// x is equal to: 5

std::endl vs

std::endl ❌

std::cout << "Hi!" << std::endl; // std::endl will cause the cursor to move to the next line of the console
std::cout << "My name is Alex." << std::endl;

// Hi!
// My name is Alex.

Prefer '\n' over std::endl when outputting text to the console because std::end moves cursor to next line + flushes buffer

✅

std::cout << "x is equal to: " << x << '\n';
std::cout << "And that's all, folks!\n";

Buffering & flushing

std::cout is buffered , meaning a buffer stores all cout until it is full then it will print the output all together into the terminal. increase efficiency as less operations to terminal.

Use std::flush to manually flush out the buffer to ensure immediate display