TweetFollow Us on Twitter

Hello World
Volume Number:2
Issue Number:5
Column Tag:The ABC's of C

Starting with Hello World

By Bob Gordon, Apropos Publications, Minneapolis, MN

Welcome to How to C. This series will explore use of the C language on the Macintosh for those who don't know C and may have fairly limited experience programming the Mac. Put another way, if you often have the feeling that you don't know what's going on, this is a place to get your bearings.

You'll find the following items useful to have around if you want to do more than program vicariously:

• Using the Macintosh Toolbox with C by Takatsuka, Huxham, and Burnard (Sybex, 1986). This will serve as our 'text.' It is currently the best available book on C on the Mac. We will generally follow their order of topics.

• The C Programming Language by Kernighan and Ritchie (Prentice-Hall, 1978). If you are going to use C, you need this book. It is an amazingly clear and concise discussion of the language.

• Inside Macintosh. Mainly because the first book does not cover everything.

• A C development system. A number of compilers are available. We'll focus on Consulair's Mac C because the Using the Macintosh Toolbox book uses it, and because it uses MDS. If you're using a different compiler, don't worry. C is one of the more portable languages (between compilers and machines), and I'll try to point out differences when they appear.

I'll also mention other useful sources of which I am aware. If you have any favorite books or articles, send me a note so we can share the information.

Why Use C / Why Not Use C

C was designed to be suitable for systems programming. As such, it is very flexible and allows programmers to do pretty much as they please. C is often characterized as a 'medium level' language. It offers the control mechanisms and data structures of a higher level language but at the same time allows access to the hardware and the ability to handle data in any way that seems suitable at the time. The compilers typically generate fairly fast, compact code.

This flexibility is not without its costs, however. It is very easy to make a real mess of things (and generate incendiary devices on the Macintosh) by not getting the types of parameters correct. And some C notation can be downright cryptic. It is easy to make C code unreadable.

In spite of the problems, I prefer C to Pascal. I could usually do what I wanted with Pascal (depending on the compiler), but I knew I was cheating. And I could never be sure the technique would work the same way with a different compiler.

Problems Using C on the Macintosh

One problem with C vis-à-vis the Macintosh is that much of the C literature and many of the standard library functions assume you are using Unix or a Unix-like operating system. As you may have noticed, the Macintosh does not. This poses an additional set of problems for learning C on the Mac. The compiler makers follow two approaches. Some ignore Unix; others make the Mac look like it's running Unix.

A second problem is that the Macintosh operating system assumes applications will be written in Pascal. This presents problems in at least two areas: strings and parameter passing.

A C string is an array of bytes with a terminating zero (a byte of all zero bits, a binary zero, the null character, represented in C by \0). A Pascal string, as far as the Macintosh is concerned, is an array of bytes consisting of a leading byte containing the number of bytes in the string followed by the bytes of the string. Obviously sending a C string to a Toolbox function is not going to yield any sort of desired result. The compiler makers have solved this problem in two ways. Some compilers automatically convert the string when its passed; others provide a C function to do the conversion that you call before calling the Toolbox function (and another function to reconvert the string). Check your compiler's documentation to see what it does.

The parameter passing problem involves a number of issues: where parameters are passed (stack or registers), the order in which they are passed, and how complex data types are passed. Most of the time you need not to be concerned with this at all; your compiler will do the necessary translations. In some cases (with some compilers) you must be aware of the difference.

Getting Started

The first program we'll do is the first program in Kernighan and Ritchie. This will force us to figure out how to set up our compiler, and use the editor, compiler, and linker. Now, at this point I should simply recount my experiences in getting "hello, world" to appear on my screen. Unhappily, I only recently received the compiler so I haven't done it yet. I also do not have two Macs so excuse me while I figure this out.

This month I've got Mac C™ from Consulair. It comes with three booklets of documentation, a letter from the author Bill Duvall, and some information sheets. One sheet describes the contents of the four disks. They include a public domain ram disk program written in Mac C called RamStart, so the first thing I did was to set up a ram disk.

Using RamStart is a bit exciting. A help button is available, but if you don't click it fast enough, RamStart goes ahead and makes the ram disk. I don't remember exactly how I found that out: it is, of course, in the instructions, but you can't read the instructions unless you click help. Catch 22. Actually, the program is quite easy to use. Simply put what you want in the ram disk in the same folder with RamStart, and it creates the disk with those files in it. With Mac C, you may not have a ram disk larger than 280 K bytes (on a 512 K machine) or the compiler will run out of room.

The Mac C package includes Edit, the four window mouse-driven program editor. Edit allows transferring directly to the compiler so you can invoke the compiler directly from Edit.

hello, world

Using Edit, I typed in the first program most people learning C try, a program to print "hello, world" on the screen.

#include  "stdio.h"

/* traditional first C program */
main()  
{
  printf("hello, world"); 
}

That's the program. If you have never seen a C program before, there is a lot to examine even in this.

The first line specifies an include file. This is a separate file that you wish to include as part of the compilation. These files typically contain constants, references to external functions, new symbols, and macros, but they can contain any code you wish to include.

Here are some parts of the stdio.h that comes with Mac C:

// stdio.h  

The double slash means comment to the end of the line. This is not standard.

// Copyright 1984 Consulair Corporation.
// All rights reserved

// Aug 30, 1984 2:43 PM: New File
// Standard UNIX IO library defs for MacC

    #define ERROR -1
    #define EOF -1
    #define NULL 0
    #define MAXLINE 255
    #define FILE int

The defines are instructions to the C preprocessor. These supply names to some oft-used values. In a program, you can use the name and the preprocessor will replace it with the value. By the way, standard C practice requires the "#" be in the first column. Mac C allows it anywhere on the line as long at is is preceded only by white space.

// Standard Routines

  extern char putchar();
  extern char fputc();
  extern long putl();
  
  extern int printf(...);

There are references to external functions. External functions are functions defined in another file. For the compiler to work correctly, it needs to know the type of object returned, if any. Here we see that putchar returns a type char, putl returns a long, and printf returns an int. Most C compilers have a separate include file for each chapter in Inside Macintosh to provide the necessary definitions.

To return to our program, the next line is:

/* traditional first C program */

This is a comment. The "/* */" bracket comments.

main()

Every C program must have one and only one main function. It is where execution starts. Function names always have parentheses after them even if they have no parameters.

{
  printf("hello,world");
}

The braces define a block of code that is handled as one line for program control purposes. They are similar to Pascal's begin-end.

The only piece of code that does anything here is printf. It is used to write strings on the screen (the standard output device). It is not actually part of the language but is part of the standard library. The semicolon is a line terminator.

A few comments are in order concerning other compilers. Mac C creates a TTY window for the standard C I/O functions. Other compilers may write directly to the desk top or require that you create a window for them. You will have to check the documentation.

Next month we'll look at some more basic C concepts and start dealing with using C in the Macintosh environment.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

FotoMagico 5.6.12 - Powerful slideshow c...
FotoMagico lets you create professional slideshows from your photos and music with just a few, simple mouse clicks. It sports a very clean and intuitive yet powerful user interface. High image... Read more
OmniGraffle Pro 7.12.1 - Create diagrams...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
beaTunes 5.2.1 - Organize your music col...
beaTunes is a full-featured music player and organizational tool for music collections. How well organized is your music library? Are your artists always spelled the same way? Any R.E.M. vs REM?... Read more
HandBrake 1.3.0 - Versatile video encode...
HandBrake is a tool for converting video from nearly any format to a selection of modern, widely supported codecs. Features Supported Sources VIDEO_TS folder, DVD image or real DVD (unencrypted... Read more
Macs Fan Control 1.5.1.6 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
TunnelBear 3.9.3 - Subscription-based pr...
TunnelBear is a subscription-based virtual private network (VPN) service and companion app, enabling you to browse the internet privately and securely. Features Browse privately - Secure your data... Read more
calibre 4.3.0 - Complete e-book library...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
Lyn 1.13 - Lightweight image browser and...
Lyn is a fast, lightweight image browser and viewer designed for photographers, graphic artists, and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it delivers... Read more
Visual Studio Code 1.40.0 - Cross-platfo...
Visual Studio Code provides developers with a new choice of developer tool that combines the simplicity and streamlined experience of a code editor with the best of what developers need for their... Read more
OmniGraffle 7.12.1 - Create diagrams, fl...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more

Latest Forum Discussions

See All

The House of Da Vinci 2 gets a new gamep...
The House of Da Vinci launched all the way back in 2017. Now, developer Blue Brain Games is gearing up to deliver a second dose of The Room-inspired puzzling. Some fresh details have now emerged, alongside the game's first official trailer. [Read... | Read more »
Shoot 'em up action awaits in Battl...
BattleBrew Productions has just introduced another entry into its award winning, barrelpunk inspired, BattleSky Brigade series. Whilst its previous title BattleSky Brigade TapTap provided fans with idle town building gameplay, this time the... | Read more »
Arcade classic R-Type Dimensions EX blas...
If you're a long time fan of shmups and have been looking for something to play lately, Tozai Games may have just released an ideal game for you on iOS. R-Type Dimensions EX brings the first R-Type and its sequel to iOS devices. [Read more] | Read more »
Intense VR first-person shooter Colonicl...
Our latest VR obsession is Colonicle, an intense VR FPS, recently released on Oculus and Google Play, courtesy of From Fake Eyes and Goboogie Games. It's a pulse-pounding multiplayer shooter which should appeal to genre fanatics and newcomers alike... | Read more »
PUBG Mobile's incoming update bring...
PUGB Mobile's newest Royale Pass season they're calling Fury of the Wasteland arrives tomorrow and with it comes a fair chunk of new content to the game. We'll be seeing a new map, weapon and even a companion system. [Read more] | Read more »
PSA: Download Bastion for free, but wait...
There hasn’t been much news from Supergiant Games on mobile lately regarding new games, but there’s something going on with their first game. Bastion released on the App Store in 2012, and back then it was published by Warner Bros. This Warner... | Read more »
Apple Arcade: Ranked - 51+ [Updated 11.5...
This is Part 2 of our Apple Arcade Ranking list. To see part 1, go here. 51. Patterned [Read more] | Read more »
NABOKI is a blissful puzzler from acclai...
Acclaimed developer Rainbow Train's latest game, NABOKI, is set to launch for iOS, Android, and Steam on November 13th. It's a blissful puzzler all about taking levels apart in interesting, inventive ways. [Read more] | Read more »
A Case of Distrust is a narrative-driven...
A Case of Distrust a narrative-focused mystery game that's set in the roaring 20s. In it, you play as a detective with one of the most private eye sounding names ever – Phyllis Cadence Malone. You'll follow her journey in San Francisco as she... | Read more »
Brown Dust’s October update offers playe...
October is turning out to be a productive month for the Neowiz team, and a fantastic month to be a Brown Dust player. First, there was a crossover event with the popular manga That Time I Got Reincarnated as a Slime. Then, there was the addition of... | Read more »

Price Scanner via MacPrices.net

Score a 37% discount on Apple Smart Keyboards...
Amazon has Apple Smart Keyboards for current-generation 10″ iPad Airs and previous-generation 10″ iPad Pros on sale today for $99.99 shipped. That’s a 37% discount over Apple’s regular MSRP of $159... Read more
Apple has refurbished 2019 13″ 1.4GHz MacBook...
Apple has a full line of Certified Refurbished 2019 13″ 1.4GHz 4-Core Touch Bar MacBook Pros available starting at $1099 and up to $230 off MSRP. Apple’s one-year warranty is included, shipping is... Read more
2019 13″ 1.4GHz 4-Core MacBook Pros on sale f...
Amazon has new 2019 13″ 1.4GHz 4-Core Touch Bar MacBook Pros on sale for $150-$200 off Apple’s MSRP. These are the same MacBook Pros sold by Apple in its retail and online stores: – 2019 13″ 1.4GHz/... Read more
11″ 64GB Gray WiFi iPad Pro on sale for $674,...
Amazon has the 11″ 64GB Gray WiFi iPad Pro on sale today for $674 shipped. Their price is $125 off MSRP for this iPad, and it’s the lowest price available for the 64GB model from any Apple reseller. Read more
2019 15″ MacBook Pros available for up to $42...
Apple has a full line of 2019 15″ 6-Core and 8-Core Touch Bar MacBook Pros, Certified Refurbished, available for up to $420 off the cost of new models. Each model features a new outer case, shipping... Read more
2019 15″ MacBook Pros on sale this week for $...
Apple resellers B&H Photo and Amazon are offering the new 2019 15″ MacBook Pros for up to $300 off Apple’s MSRP including free shipping. These are the same MacBook Pros sold by Apple in its... Read more
Sunday Sale: AirPods with Wireless Charging C...
B&H Photo has Apple AirPods with Wireless Charging Case on sale for $159.99 through 11:59pm ET on November 11th. Their price is $40 off Apple’s MSRP, and it’s the lowest price available for these... Read more
Details of Sams Club November 9th one day App...
Through midnight Saturday night (November 9th), Sams Club online has several Apple products on sale as part of their One Day sales event. Choose free shipping or free local store pickup (if available... Read more
Sprint is offering the 64GB Apple iPhone 11 f...
Sprint has the new 64GB iPhone 11 available for $15 per month for new lines. That’s about 50% off their standard monthly lease of $29.17. Over is valid until November 24, 2019. The fine print: “Lease... Read more
New Sprint November iPhone deal: Lease one iP...
Switch to Sprint and purchase an Apple iPhone 11, 11 Pro, or 11 Pro Max, and get a second 64GB iPhone 11 for free. Requires 2 new lines or 1 upgrade-eligible line and 1 new line. Offer is valid from... Read more

Jobs Board

*Apple* Mobility Pro - Best Buy (United Stat...
**746087BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000319-Harlem & Irving-Store **Job Description:** Read more
Best Buy *Apple* Computing Master - Best Bu...
**743392BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Store Associates **Store NUmber or Department:** 001171-Southglenn-Store **Job Read more
Best Buy *Apple* Computing Master - Best Bu...
**746015BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Store NUmber or Department:** 000372-Federal Way-Store **Job Description:** Read more
*Apple* Mobility Pro - Best Buy (United Stat...
**744658BR** **Job Title:** Apple Mobility Pro **Job Category:** Store Associates **Store NUmber or Department:** 000586-South Hills-Store **Job Description:** At Read more
Best Buy *Apple* Computing Master - Best Bu...
**741552BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Store NUmber or Department:** 000277-Metcalf-Store **Job Description:** **What Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.