FREE

[Gordon Burditt]

>|    Why is NOT malloc() made to initialize the contents automatically?
>Why would you spend time on this, if you have to put data into the area anyway?
>I believe this is by far the most common use.

I have on occasion put my own wrapper around malloc() to initialize the
allocated memory area.  The data to use for initialization was chosen so
that (some of these objectives are processor-dependent):

- If it's used as a pointer, you get a segmentation violation.
- If it's used as a function pointer, it should be odd so you trap immediately.
- If it's used as a floating point number, you get a number with an
  obnoxiously large exponent that's likely to overflow in calculations.
- If it's used as an integer, it's very large and negative.
- If it's printed in hex, it's recognizable.

One number I used for this was the 4-byte constant: 0xdeadbee1.  On
another occasion I used the negative of the time().

I would like to add one criteria I couldn't satisfy:
- If it's printed as a string, it's an obscenity.

Also, it's very important that no portion of the program EXCEPT the wrapper
around malloc() know what the constant is or any of its attributes.

Using this technique with a program that made extensive use of linked lists
helped to quickly trap failure to initialize back link pointers close to the 
point of the problem.  After the program is working (you think), you can
take out the debugging initialization part to speed up the program.

						Gordon L. Burditt
						sneaky.lonestar.org!gordon