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c [2015/12/31 09:29]
admin [Have it reviewed]
c [2020/10/17 09:05] (current)
114.119.151.1 ↷ Links adapted because of a move operation
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-=====Writing C=====+====== Decent C======
 I've been writing c for over 30 years, but it can still be a nightmare - the problems are well documented elsewhere. The discipline of writing device drivers for Linux/Solaris/HP-UX/AIX etc etc and crypto code for RSA (thanks, Michael for the excellent code-reviews - I learned so much) have led to a few points that help make code clearer, easier to maintain and less likely to contain memory leaks and other faults. I've been writing c for over 30 years, but it can still be a nightmare - the problems are well documented elsewhere. The discipline of writing device drivers for Linux/Solaris/HP-UX/AIX etc etc and crypto code for RSA (thanks, Michael for the excellent code-reviews - I learned so much) have led to a few points that help make code clearer, easier to maintain and less likely to contain memory leaks and other faults.
 ====Single return point==== ====Single return point====
-Every routine should have a single return point. All possible execution paths go through this point and therefore have the chance to have resources released. The main thing, of course, is to free resources that are no longer needed eg memory that has been malloc()'ed, file/socket descriptors and in device drivers, to release DMA and interrupt resources.+Every routine should have a single return point. All possible execution paths go through this point and therefore have the chance to have resources released. The main thing, of course, is to free resources that are no longer needed eg memory that has been malloc()'ed, file/socket descriptors and in device drivers, to release DMA and interrupt resources. See the following example.
 ====Error responses should be close to the failing statement==== ====Error responses should be close to the failing statement====
 and not dangling at the end of some huge }}}} block ten pages away!!! Deal with it _now_, to hell with making the Happy Path clearer - the Happy Path is easy, it's the errors that make the thing beastly. and not dangling at the end of some huge }}}} block ten pages away!!! Deal with it _now_, to hell with making the Happy Path clearer - the Happy Path is easy, it's the errors that make the thing beastly.
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 Do it even when it looks stupidly simple - later, when the routine is made more elaborate, then the logic is in place and you will remember to cleanup: Do it even when it looks stupidly simple - later, when the routine is made more elaborate, then the logic is in place and you will remember to cleanup:
  
-<code>+<code c>
 /* @return 0 if file is foobarable. Otherwise 1.  /* @return 0 if file is foobarable. Otherwise 1. 
  */  */
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 ====exit values etc==== ====exit values etc====
 Unless you've got a really good excuse, the program should exit(0) on success and non-zero on failure (note that exit code can only be up to 8-bits long). Unless you've got a really good excuse, the program should exit(0) on success and non-zero on failure (note that exit code can only be up to 8-bits long).
-As with [[DecentBash]], the program should send error messages (prefixed with the program name) to stderr, output to stdout. It should recognise -h (no matter what) and possibly --help and print help to stdout (and return 0!). -v and --verbose are also pretty standard.+As with [[unixscripts:3-decentbash]], the program should send error messages (prefixed with the program name) to stderr, output to stdout. It should recognise -h (no matter what) and possibly --help and print help to stdout (and return 0!). -v and --verbose are also pretty standard.
  
 In fact, why not use argp(3) to make option processing easy? In fact, why not use argp(3) to make option processing easy?
c.1451554191.txt.gz · Last modified: 2015/12/31 09:29 by admin