Merge pull request #186 from chrboesch/c_math

added C math exercise
This commit is contained in:
Chris Boesch 2023-02-18 23:52:08 +01:00 committed by GitHub
commit f6a2356bea
4 changed files with 44 additions and 2 deletions

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@ -471,7 +471,12 @@ const exercises = [_]Exercise{
}, },
.{ .{
.main_file = "093_hello_c.zig", .main_file = "093_hello_c.zig",
.output = "Hello C from Zig! - C result ist 17 chars", .output = "Hello C from Zig! - C result ist 17 chars written.",
.C = true,
},
.{
.main_file = "094_c_math.zig",
.output = "The normalized angle of 765.2 degrees is 45.2 degrees.",
.C = true, .C = true,
}, },
.{ .{

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@ -57,7 +57,7 @@ pub fn main() void {
const c_res = write(2, "Hello C from Zig!", 17); const c_res = write(2, "Hello C from Zig!", 17);
// let's see what the result from C is: // let's see what the result from C is:
std.debug.print(" - C result ist {d} chars\n", .{c_res}); std.debug.print(" - C result ist {d} chars written.\n", .{c_res});
} }
// //
// Something must be considered when compiling with C functions. // Something must be considered when compiling with C functions.

33
exercises/094_c_math.zig Normal file
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@ -0,0 +1,33 @@
//
// Often C functions are used where no equivalent Zig function exists
// yet. Since the integration of a C function is very simple as already
// seen in the last exercise, it naturally offers itself to use the
// very large variety of C functions for the own programs.
// In addition immediately an example:
//
// Let's say we have a given angle of 765.2 degrees. If we want to
// normalize that, it means that we have to subtract X * 360 degrees
// to get the correct angle. How could we do that? A good method is
// to use the modulo function. But if we write "765.2 % 360", it won't
// work, because the standard modulo function works only with integer
// values. In the C library "math" there is a function called "fmod".
// The "f" stands for floating and means that we can solve modulo for
// real numbers. With this function it should be possible to normalize
// our angel. Let's go.
const std = @import("std");
const c = @cImport({
// What do wee need here?
???
});
pub fn main() !void {
const angel = 765.2;
const circle = 360;
// Here we call the C function 'fmod' to get our normalized angel.
const result = c.fmod(angel, circle);
std.debug.print("The normalized angle of {d: >3.1} degrees is {d: >3.1} degrees.\n", .{ angel, result });
}

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@ -0,0 +1,4 @@
22c22
< ???
---
> @cInclude("math.h");