Adding zig calling c.

current/algorithms/callingc_zig/.gitignore

@@ -0,0 +1,2 @@
+.zig-cache
+zig-out

current/algorithms/callingc_zig/build.zig

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+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const exe = b.addExecutable(.{
+        .name = "callingc",
+        .root_source_file = b.path("src/callingc.zig"),
+        .target = b.host,
+        .optimize = b.standardOptimizeOption(.{}),
+    });
+    exe.addIncludePath(b.path("c-src"));
+    exe.addCSourceFile(.{ .file = b.path("c-src/callingc.c") });
+    b.installArtifact(exe);
+
+    const run_cmd = b.addRunArtifact(exe);
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    const run_step = b.step("run", "run the app");
+    run_step.dependOn(&run_cmd.step);
+}

current/algorithms/callingc_zig/c-src/callingc.c

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+#include "callingc.h"
+
+int add_numbers(int a, int b) {
+  return 2*a+b;
+}

current/algorithms/callingc_zig/c-src/callingc.h

@@ -0,0 +1 @@
+int add_numbers(int a, int b);

current/algorithms/callingc_zig/src/callingc.zig

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+const std = @import("std");
+
+const callingc = @cImport({
+    @cInclude("callingc.h");
+});
+
+pub fn main() !void {
+    const stdout_file = std.io.getStdOut().writer();
+    var bw = std.io.bufferedWriter(stdout_file);
+    const stdout = bw.writer();
+
+    const c = callingc.add_numbers(3, 4);
+
+    try stdout.print("Hello World {d}!!\n", .{c});
+    try bw.flush();
+}