Merge pull request #247 from chrboesch/formatting

added first formatting exercise
This commit is contained in:
Chris Boesch 2023-04-19 22:09:32 +02:00 committed by GitHub
commit 4435cebe7a
4 changed files with 125 additions and 1 deletions

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@ -179,7 +179,7 @@ Core Language
* [ ] Async <--- IN PROGRESS!
* [X] Interfaces
* [X] Working with C
* [ ] String formatting
* [X] String formatting
* [X] Bit manipulation
## Contributing

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@ -514,6 +514,10 @@ const exercises = [_]Exercise{
.main_file = "098_bit_manipulation2.zig",
.output = "Is this a pangram? true!",
},
.{
.main_file = "099_formatting.zig",
.output = "\n X | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 \n---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+\n 1 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 \n\n 2 | 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 \n\n 3 | 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 \n\n 4 | 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 \n\n 5 | 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 \n\n 6 | 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 \n\n 7 | 7 14 21 28 35 42 49 56 63 70 77 84 91 98 105 \n\n 8 | 8 16 24 32 40 48 56 64 72 80 88 96 104 112 120 \n\n 9 | 9 18 27 36 45 54 63 72 81 90 99 108 117 126 135 \n\n10 | 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 \n\n11 | 11 22 33 44 55 66 77 88 99 110 121 132 143 154 165 \n\n12 | 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 \n\n13 | 13 26 39 52 65 78 91 104 117 130 143 156 169 182 195 \n\n14 | 14 28 42 56 70 84 98 112 126 140 154 168 182 196 210 \n\n15 | 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 \n\n",
},
.{
.main_file = "999_the_end.zig",
.output = "\nThis is the end for now!\nWe hope you had fun and were able to learn a lot, so visit us again when the next exercises are available.",

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@ -0,0 +1,115 @@
//
// The output on the console looks a bit rudimentary at first glance.
// However, if you look at the development of modern computers, you can
// see the enormous progress that has been made over the years.
// Starting with monochrome lines on flickering CRT monitors, modern
// terminal emulators offer a razor-sharp image with true color and
// nearly infinite font size thanks to modern hardware.
//
// In addition, they have mastered ligatures and can represent almost
// any character in any language. This also makes the output of programs
// on the console more atractive than ever in recent years.
//
// This makes it all the more important to format the presentation of
// results in an appealing way, because that is what users appreciate,
// quick visual comprehension of the information.
//
// C has set standards here over the years, and Zig is preparing to
// follow suit. Currently, however, it still lags a bit behind the model,
// but the Zig community is working diligently behind the scenes on
// further options.
//
// Nevertheless, it is time to take a closer look at the possibilities
// that already exist. And of course we will continue this series loosely,
// because Zig continues to grow almost daily.
//
// Since there is no proper documentation on the formatting yet, the most
// important source here is the source code:
//
// https://github.com/ziglang/zig/blob/master/lib/std/fmt.zig#L29
//
//
// And in fact, you already discover quite a lot of useful formatting.
// These can be used in different ways, e.g. to convert numerical values
// into text and for direct output to the console or to a file. The latter
// is useful when large amounts of data are to be processed by other programs.
//
// However, we are concerned here exclusively with the output to the console.
// But since the formatting instructions for files are the same, what you
// learn applies universally.
//
// Since we basically write to debug output in Ziglings, our output usually
// looks like this:
//
// std.debug.print("Text {placeholder} another text \n", .{variable});
//
// But how is the statement just shown formatted?
//
// This actually happens in several stages. On the one hand, escape
// sequences are evaluated, there is the "\n" which means "line feed"
// in the example. Whenever this statement is found, a new line is started
// in the output. Escpape sequences can also be written one after the
// other, e.g. "\n\n" will cause two line feeds.
//
// By the way, these formattings are passed directly to the terminal
// program, i.e. escape sequences have nothing to do with Zig in this
// respect. The formatting that Zig actually performs is found in the
// curly bracket, the "placeholder", and affects the coresponding variable.
//
// And this is where it gets exciting, because numbers can have different
// sizes, be positive or negative, with a decimal point or without,
// and so on.
//
// In order to bring these then into a uniform format for the output,
// instructions can be given to the placeholder:
//
// print("=> {x:0>4}", .{var});
//
// This instruction outputs a hexadecimal number with leading zeros.
//
// => 0x0017
//
// Let's move on to our exercise: we want to create a table that shows us
// the multiplication of all numbers together from 1-15. So if you search
// for the number '5' in the row and '4' in the column (or vice versa),
// the result of '5 x 4 = 20' should be displayed there.
//
//
const std = @import("std");
const print = std.debug.print;
pub fn main() !void {
// the max. size of the table
const size = 15;
// print the header:
//
// we start with a single 'X' for the diagonal,
// that means there is no result
print("\n X |", .{});
// header row with all numbers from 1 to size
for (0..size) |n| {
print("{d:>3} ", .{n + 1});
}
print("\n", .{});
// row line
var n: u8 = 0;
while (n <= size) : (n += 1) {
print("---+", .{});
}
print("\n", .{});
// now the actual table
for (0..size) |a| {
print("{d:>2} |", .{a + 1});
for (0..size) |b| {
// what formatting is needed here?
print("{???} ", .{(a + 1) * (b + 1)});
}
// after each row we use double line feed
print("\n\n", .{});
}
}

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@ -0,0 +1,5 @@
108,109c108
< // what formatting is needed here?
< print("{???} ", .{(a + 1) * (b + 1)});
---
> print("{d:>3} ", .{(a + 1) * (b + 1)});