For 2023 - 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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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))
Dynamic Memory Allocation in C
In C, you give fixes sizes for arrays at compile time .... which means you either have to know ahead of time how big something will be, or allow enough space for the worst case scenario.
Rather than using arrays, you can use pointers to the memory heap - and in this way you can use functions to give you dynamic memory allocation:
malloc - allocate a specific memory block
calloc - allocate an array of specific memory blocks
realloc - expand or contract a calloced block
free - release a malloced block
cfree - release a realloced block
There's an example showing how these functions can be used to dynamically load a file with a variable number of variable length records here (written 2008-06-09, updated 2008-06-10)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articlesC212 - C and C based languages - Memory Management 
Training Season Starts again! - (2008-01-07) 
What is an lvalue? (Perl, C) - (2008-03-18) 
Dynamic Memory Allocation in C - calloc, realloc - (2008-03-22) 
Passing a table from Lua into C - (2008-10-18) 
Efficient use of dynamic memory - C and realloc - (2010-03-10) 
C course - final course example puts it all together - (2010-07-02) 
Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02) 
Setting up arrays in C - fixed size at compile time, or dynamic - (2011-01-24) 
Adding the pieces together to make a complete language - C - (2011-08-11) 
Storing Tcl source code encoded, and running via your own C program - (2011-09-02) 
Allocating memory dynamically in a static language like C - (2013-06-30) 
Simple C structs - building up to full, dynamic example - (2014-12-03) 
Regression testing - via a very short C testing framework - (2016-01-29) 
Encapsulating logic in functions and structs - the C approach to Object Oriented techniques - (2016-01-30)
Some other Articles
What a lot of files! (C++ / Polymorphism demo)Spam Filters ... are working!The Composting Cone ChallengeCompiling C programs with gcc - an overviewDynamic Memory Allocation in CWhat are Unions (C programming)Talk on TransWilts train service to Green PartyChecking server performance for PHP generated pagesSlow boot and terminal start on Linux boxesFactory method example - Perl
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