Criticism of the C programming language: Difference between revisions

Revision as of 18:11, 31 August 2006

Revision as of 05:32, 1 September 2006

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===Arrays===

Although C supports static arrays, it is not required that array indexes be validated ([[bounds checking]]). For example, one can write to the sixth element of an array with five elements, yielding generally undesirable results. This type of bug, called a ''[[buffer overflow]],'' has been notorious as the source of a number of security problems. On the other hand, since [[bounds checking elimination]] technology was largely nonexistent when C was defined, bounds checking came with a severe performance penalty, particularly in numerical computation. By comparison, a few years earlier, some [[Fortran]] compilers had a switch to toggle bounds checking on or off; however, this would have been much less useful for C, where array arguments are passed as simple pointers.

Multidimensional arrays are commonly used in numerical algorithms (mainly from applied linear algebra) to store matrices. The structure of the C array is particularly well suited to this particular task, provided one remembers to count indices starting from 0 instead of 1. This issue is discussed in the book ''[[Numerical Recipes|Numerical Recipes in C]]'', chapter 1.2, page 20''ff'' ([http://www.library.cornell.edu/nr/bookcpdf/c1-2.pdf read online]). In that book there is also a solution based on negative indexing which introduces other dangers. Starting indices at 0 has been assimilated into the computing culture, and is no longer as alien a notion as it seemed when C was first introduced.