Shows why early exit on failure is a good code style strategy.

early_exit.cc

/*
  In this snippet, the failure cases are not close to the conditions they belong to.
  This makes it hard to track when which error case is triggered (especially when they are more than a screen height apart).

  It also adds a lot of `{}` and indentation.
*/
int someFunction(int foo, int bar, int baz)
{
    if (foo == 1)
    {
        if (bar == 2)
        {
            if (baz == 3)
            {
                std::cout << "Success!\n";
                return true;
            }
            else
            {
                std::cout << "ERROR: edge case 3 not supported;\n";
                exit(3);
            }
        }
        else
        {
            std::cout << "ERROR: edge case 2 not supported;\n";
            exit(2);
        }
    } 
    else
    {
        std::cout << "ERROR: edge case 1 not supported;\n";
        exit(1);
    }
}

/* 
 The same function, but this time with early exit on failure.
 The error cases are directly connected to their conditions.

 Also, there is no extra indentation happening.
*/
int someFunction(int foo, int bar, int baz)
{
    if (foo != 1)
    {
        std::cout << "ERROR: edge case 1 not supported;\n";
        exit(1);
    }
    if (bar != 2)
    {
        std::cout << "ERROR: edge case 2 not supported;\n";
        exit(2);
    }
    if (baz != 3)
    {
        std::cout << "ERROR: edge case 3 not supported;\n";
        exit(3);
    }

    std::cout << "Success!\n";
    return true;

}