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78 lines
2.7 KiB
Zig
78 lines
2.7 KiB
Zig
//
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// When Andrew Kelley announced the idea of a new programming language
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// - namely Zig - in his blog on February 8, 2016, he also immediately
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// stated his ambitious goal: to replace the C language!
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//
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// In order to be able to achieve this goal at all, Zig should be
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// as compatible as possible with its "predecessor".
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// Only if it is possible to exchange individual modules in existing
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// C programs without having to use complicated wrappers,
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// the undertaking has a chance of success.
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//
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// So it is not surprising that calling C functions and vice versa
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// is extremely "smooth".
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//
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// To call C functions in Zig, you only need to specify the library
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// that contains said function. For this purpose there is a built-in
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// function corresponding to the well-known @import():
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//
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// @cImport()
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//
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// All required libraries can now be included in the usual Zig notation:
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//
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// const c = @cImport({
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// @cInclude("stdio.h");
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// @cInclude("...");
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// });
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//
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// Now a function can be called via the (in this example) constant 'c':
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//
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// c.puts("Hello world!");
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//
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// By the way, most C functions have return values in the form of an
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// integer value. Errors can then be evaluated (return < 0) or other
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// information can be obtained. For example, 'puts' returns the number
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// of characters output.
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//
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// So that all this does not remain a dry theroy now, let's just start
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// and call a C function out of Zig.
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//
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// our well-known "import" for Zig
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const std = @import("std");
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// new the import for C
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const c = @cImport({
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// we use "standard input/output" from C
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@cInclude("stdio.h");
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});
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pub fn main() void {
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// Due to a current limitation in the Zig compiler,
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// we need a small workaround to make this exercise
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// work on mac-os.
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const builtin = @import("builtin");
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const stderr = switch (builtin.target.os.tag) {
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.macos => 1,
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else => c.stderr,
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};
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// In order to output a text that can be evaluated by the
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// Zig Builder, we need to write it to the Error output.
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// In Zig we do this with "std.debug.print" and in C we can
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// specify the file to write to, i.e. "standard error (stderr)".
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//
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// Ups, something is wrong...
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const c_res = fprintf(stderr, "Hello C from Zig!");
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// let's see what the result from C is:
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std.debug.print(" - C result ist {d} chars\n", .{c_res});
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}
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//
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// Something must be considered when compiling with C functions.
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// Namely that the Zig compiler knows that it should include
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// corresponding libraries. For this purpose we call the compiler
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// with the parameter "lc" for such a program,
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// e.g. "zig run -lc hello_c.zig".
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//
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