Using scanf to accept user input

Question

gcc 4.4.2

I was reading an article about scanf. I personally have never checked the return code of a scanf.

#include 

int main(void)
         


        

Answer 1

Don't use scanf directly. It's surprisingly hard to use. It's better to read an entire line of input and to then parse it (possibly with sscanf).

Read this entry (and the entries it references) from the comp.lang.c FAQ: http://c-faq.com/stdio/scanfprobs.html

Edit: Okay, to address your additional question from your own edit: If you allow unstructured input, then you're going to have to attempt to parse the string in multiple ways until you find one that works. If you can't find a valid match, then you should reject the input and prompt the user again, probably explaining what format you want the input to be in.

For anything more complicated, you'd probably be better off using a regular expression library or even using dedicated lexer/parser toolkits (e.g. flex and bison).