Zig
Get the Value of a MIME Header Field

Demonstrates how to get the value of a MIME header field. If the header field is not in the top-level MIME header, we must first navigate to the correct MIME part.
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const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    const mime = try chilkat.Mime.init();
    defer mime.deinit();

    // The contents of this MIME file are shown below,
    // and is also available at https://www.chilkatsoft.com/sampleMime.txt
    mime.loadMimeFile("qa_data/mime/sampleMime.txt") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // The MIME used in this example has the following nested structure
    //
    // multipart/alternative
    //     text/plain
    //     multipart/related
    //         text/html
    //         image/jpeg
    //

    // Getting the content of a top-level MIME header is easy.
    // MIME header fields are case insensitive.
    std.debug.print("Subject = {s}\n", .{try mime.getHeaderField(alloc, "subject")});
    std.debug.print("MIME-Version = {s}\n", .{try mime.getHeaderField(alloc, "mime-version")});

    // To get a MIME header in a sub-part, first navigate to it..

    const mp_related = try chilkat.Mime.init();
    defer mp_related.deinit();
    mime.partAt(1, mp_related) catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    const p_jpg = try chilkat.Mime.init();
    defer p_jpg.deinit();
    mp_related.partAt(1, p_jpg) catch {
        std.debug.print("{s}\n", .{try mp_related.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("JPG Content-ID = {s}\n", .{try p_jpg.getHeaderField(alloc, "content-id")});
    std.debug.print("JPG Content-Type = {s}\n", .{try p_jpg.getHeaderField(alloc, "content-type")});

    // --------------------------------------------------------------
    // --------------------------------------------------------------
    // The MIME sample file loaded at the beginning of this example
    // contains the following MIME:

    // Subject: Test email.
    // Content-Type: multipart/alternative;
    //     boundary="------------DB171738719FB06D67DEBAA0"
    // MIME-Version: 1.0
    //
    // --------------DB171738719FB06D67DEBAA0
    // Content-Type: text/plain; charset="utf-8"; format=flowed
    // Content-Transfer-Encoding: 7bit
    //
    // This is a test.
    //
    // --------------DB171738719FB06D67DEBAA0
    // Content-Type: multipart/related;
    //     boundary="------------A940F1230E6F0105F03DB2CB"
    //
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: text/html; charset="utf-8"
    // Content-Transfer-Encoding: 8bit
    //
    // <html><head>
    // <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    //   </head>
    //   <body bgcolor="#FFFFFF" text="#000000">
    //     <p>This is a test.&nbsp; <img src="cid:part1.E16AE3B4.1505C436@chilkatsoft.com" height="20" width="20"></p>
    //   </body>
    // </html>
    //
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: image/jpeg; name="starfish20.jpg"
    // Content-Transfer-Encoding: base64
    // Content-ID: <part1.E16AE3B4.1505C436@chilkatsoft.com>
    // Content-Disposition: inline; filename="starfish20.jpg"
    //
    // /9j/4AAQSkZJRgABAQEASABIAAD//gAmRmlsZSB3cml0dGVuIGJ5IEFkb2JlIFBob3Rvc2hvcD8g
    // NC4w/9sAQwAQCwwODAoQDg0OEhEQExgoGhgWFhgxIyUdKDozPTw5Mzg3QEhcTkBEV0U3OFBtUVdf
    // YmdoZz5NcXlwZHhcZWdj/9sAQwEREhIYFRgvGhovY0I4QmNjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj
    // Y2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj/8IAEQgAFAAUAwERAAIRAQMRAf/EABcAAAMBAAAA
    // AAAAAAAAAAAAAAIDBAX/xAAYAQADAQEAAAAAAAAAAAAAAAABAgMEAP/aAAwDAQACEAMQAAAB2kZY
    // NNEijWKddfTmLgALWH//xAAbEAACAgMBAAAAAAAAAAAAAAABAgMRAAQSE//aAAgBAQABBQL0XqN+
    // pM2aqJGMiqFFCyg7z//EABwRAAICAgMAAAAAAAAAAAAAAAERAAIQIQMSUf/aAAgBAwEBPwHqU5aq
    // Axx+y1tMQl4elj//xAAcEQEAAQUBAQAAAAAAAAAAAAABEQACEBIhA1H/2gAIAQIBAT8B3Bhqy7Zc
    // enyiwmGgDhiOzj//xAAdEAABAwUBAAAAAAAAAAAAAAABAAIREBIhIkFR/9oACAEBAAY/ArZyn+Cg
    // xtxWuJaoCnqDuin/xAAcEAABBAMBAAAAAAAAAAAAAAABABEhYRAxQVH/2gAIAQEAAT8hkEwPUUR9
    // DYfE4nxtRpIkBTsayuALIiuY/9oADAMBAAIAAwAAABDWPTsf/8QAGhEAAwADAQAAAAAAAAAAAAAA
    // AAEREDFBIf/aAAgBAwEBPxC0DVPcWm+Ce4OesrkE6bjH/8QAGBEBAQEBAQAAAAAAAAAAAAAAAREA
    // QRD/2gAIAQIBAT8QahMiOc8YgSrnTY3ELclHXn//xAAcEAEBAAIDAQEAAAAAAAAAAAABEQAhMUFx
    // EFH/2gAIAQEAAT8Qn3igmSZSj+c4N4zapMy9IjFV98wncN2iuLFsCEbDGxQkI6RO/n//2Q==
    //
    // --------------A940F1230E6F0105F03DB2CB--
    //
    // --------------DB171738719FB06D67DEBAA0--
    //
}