Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
C Structs - what, how and why

If you want to hold a whole series of different values about something in a C program, you'll define yourself a structure (or struct.). You give a type and name to each of the elements in the structure, and then you give an overall variable name to each instance of the struct that you create.

Here, for example, I am defining a type called "result" - to hold everything about the results of a test, for example:

typedef struct {
     int lowlim;
     int highlim;
     int pass;
     int range;
     float dut_out;
     } result;

So far, I have only defined a type .. not any actual variables that contain results; I can declare those in the way I normally declare variables, including defining pointers to them if I wish:

  result *current
  result first;
  result second;

Elements within a structure variable can be referenced (set or read) using a "." notation - for example:

  second.dut_out = 50.0;
  printf("The range was %d\n",second.range);

If you want to reference elements within a referenced struct (such as current in our example) you COULD write:
but that gets messy and an alternative, bracket-free notation is available:

You'll use pointers to structs very commonly indeed - to pass them around between function, to define them dynamically with calloc and realloc, etc.

Full source code example, showing all the things I have mentioned above, [HERE].

(written 2010-01-13)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
C209 - C and C based languages - Structures and Unions
  [1478] Some new C programming examples - files, structs, unions etc - (2007-12-19)
  [1572] C - structs and unions, C++ classes and polymorphism - (2008-03-13)
  [1584] Using Structs and Unions together effectively in C - (2008-03-21)
  [1669] What are Unions (C programming) - (2008-06-08)
  [3122] When is a program complete? - (2011-01-06)
  [3145] Structures v Structure Pointers in C. How, which, why. - (2011-01-25)
  [3386] Adding the pieces together to make a complete language - C - (2011-08-11)

Back to
The what and why of C pointers
Previous and next
Horse's mouth home
Forward to
Summary of Wiltshire Core Strategy responses
Some other Articles
Complete teaching example - C++, inheritance, polymorphism
What does const mean? C and C++
Sharing variables between files of code in C - extern
Summary of Wiltshire Core Strategy responses
C Structs - what, how and why
The what and why of C pointers
Reading and writing files in C
Function Prototypes in C
How to run a successful online poll / petition / survey / consultation
Forums for your Melksham and open source discussions
4759 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page

This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2024: 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/2573_C-S ... d-why.html • PAGE BUILT: Sun Oct 11 16:07:41 2020 • BUILD SYSTEM: JelliaJamb