Guide To Learn
There are a few different ways for a program to get input from the user. One is the so-called standard input, where the program waits for the user to enter data through the keyboard. This approach is useful when the program’s flow depends on users’ input. If you’re old enough to have grown up with […]
The simplest way to model human-readable date and time is by defining a data structure with integer components for each date and time unit. I say human-readable because most of us are quite used to thinking of dates in terms of years, months, and days, and times in terms of a 24-hour clock. A notable […]
In the first part of the implementation, we’ll define a datetime class and learn how to load it from command-line arguments and from local machine time.
From our specifications list, it looks like we’ll need some clever way to handle date and time data, as well as the time difference. In chapter 8, we learned how to define arbitrary data structures using derived types. We can thus model dates, times, and time difference structures as derived types (or classes)–let’s call these datetime and timedelta, […]
For the app to do well the one thing it’s supposed to do, it helps to set some specifications so we can plan the implementation: This specification list is plenty for this exercise. Now for the difficult part–how do we get this thing to work?
Do one thing and do it well. –A UNIX philosophy Our project for this chapter is a minimal countdown app for the command line. Following the old UNIX philosophy, it will do one thing and do it well. The app will read a year, month, and day as command-line arguments input by the user. If […]
In chapter 8, we implemented the tsunami solver using the Field derived type to model physical fields such as water height and velocity. This allowed us to initialize the fields and express the solver equation cleanly and concisely, as shown in the following listing. Listing 9.9 Main tsunami solver using the Field derived type ❶ Imports the type from the […]
As of the previous chapter, we were already using some generic procedures and custom operators in the tsunami simulator. We’ll explore their implementation in depth in the next chapter. For now, I’ll give you a taste of what’s to come.
To wrap up the chapter, in this section we’ll practice redefining Fortran’s built-in operators to do something more or other than originally intended. For example, this could involve either of the following: I leave this one as an exercise for you (“Exercise 2” sidebar). It’s a fairly new concept, but we’ve already covered all the […]
A custom operator is essentially a procedure under the hood, with an extended syntax that allows it to be used in expressions much like built-in operators: Once we have a function or a subroutine, it’s straightforward to implement it as a custom operator. Tip Don’t confuse the custom operator syntax, .op. with the logical literal constants .true. or .false.. The latter […]