NEW SERVER - 11.9.2020 ... Retiring, March 2020 - sorry, you have missed our final public course.
The Coronavirus situation has lead us to suspend public training - which was on the cards anyway, with no plans to resume
Please ask about private 'maintenance' training for Python, Tcl, Perl, PHP, Lua, etc
Happily continuing private consultancy / programming work
Strings in C
Strings in C are null terminated char arrays ... so you always need to allocate one more array member for them than the maximum possible length - to hold a string of up to 20 chars, you need an array of 21.
Double quoted string constants are null terminated strings, and if you assign them to a variable, you're assigning a pointer to the first character. But single quotes give you a single char variable, not an address. This means that you can compare chars using an == operator (you're comparing the characters) but you can't meaningfully compare strings with ==, and you would be comparing the addresses and would get a false
return if you compared two identical strings which were held at different places in memory. Instead, you should use something like strcmp
to compare strings.
There's a fresh example of some string manipulation [here]
, and examples of command line string handling [here]
. Wrong and right ways of comparing are shown [here]
There are many aspects of C which make it more complex to learn (and slower to code in) than languages like Python and Perl, but there are times when it's the right choice - for low level coding, code that has to run many time and very efficiency, and code that must be very small. So there are time when, not withstanding the complexity, people need to learn to program with C as their target language. It's a niche requirement these days - our specialty - and so we'll welcome you if you're a newcomer to programming on our Learning to program in C course
. For people who have already programmed, but need to learn / convert to C, we offer a shorter conversion course - C Programming
... I'm running it this week, and it comes up again every 2 or 3 months through the year. (written 2011-01-25)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articlesC206 - C and C based languages - Character Strings 
String handling in C - new examples of extracting integers from a string - (2016-01-27) 
Strings in C - strncmp strncpy and friends - (2015-10-27) 
Simple C structs - building up to full, dynamic example - (2014-12-03) 
Splitting a record into individual data values in C - (2012-05-04) 
Chars, char arrays and strings in C. Some early cautions and pitfalls. - (2012-01-26) 
Setting up arrays in C - fixed size at compile time, or dynamic - (2011-01-24) 
When is a program complete? - (2011-01-06) 
Learning about Regular Expressions in C through examples - (2010-06-30) 
String functions in C - (2010-06-30) 
Handling Binary data in Tcl (with a note on C) - (2007-09-09)
Some other Articles
Python dictionaries - mutable and immutable keys and valuesLooking back at www.wellho.netOpenGL / C / C++ - an example to get you startedHotel star ratings - towards a better system of reviewStrings in CStructures v Structure Pointers in C. How, which, why.On timePrivate and Public - and things betweenWiltshire Rail services - a golden opportunity
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