Null-terminated string: Difference between revisions

Revision as of 18:15, 14 May 2018

Revision as of 22:11, 20 August 2018

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Many attempts to make C string handling less error prone have been made. One strategy is to add safer functions such as <code>[[strdup]]</code> and <code>[[strlcpy]]</code>, whilst [[C standard library#Buffer overflow vulnerabilities | deprecating the use of unsafe functions]] such as <code>[[gets() | gets]]</code>. Another is to add an object-oriented wrapper around C strings so that only safe calls can be done. Neither has had a huge success as it is always possible and tempting to call the unsafe functions anyway.

Most modern libraries replace C strings with a structure containing a 32-bit or larger length value (far more than were ever considered for length-prefixed strings), and often add another pointer, a reference count, and even a NUL to speed up conversion back to a C string!. Memory is far larger now, such that if the addition of 3 (or 16, or more) bytes to each string is a real problem the software will have to be dealing with so many small strings that some other storage method will save even more memory (for instance there may be so many duplicates that a [[hash table]] will use less memory). Examples include the [[C++]] [[Standard Template Library]] <code>[[String (C++)|std::string]]</code>, the [[Qt (toolkit)|Qt]] <code>QString</code>, the [[Microsoft Foundation Class Library|MFC]] <code>CString</code>, and the C-based implementation <code>CFString</code> from [[Core Foundation]] as well as its [[Objective-C]] sibling <code>NSString</code> from [[Foundation Kit|Foundation]], both by Apple. More complex structures may also be used to store strings such as the [[rope (computer science)|rope]].

==See also==