11–20 of 178 posts
I won't pretend to know C but suppose you have a string that is 'ab{100}\0' and you wanted to remove all of the bs, you'd end up with 'a\0b{99}\0' in memory correct?
Am I OCD when I cringe when I see 'p_rite' where he (I think) means 'p_write'? That alone would knock a few points off a candidate doing this test when he's interviewing with me. 'rite' can mean 'write' or 'right' or even 'allright' - why the unnecessary confusion?
hmm, is it normal to assume all strings in C are \0 terminated? What are the memory usage implications for that? I won't pretend to know C but suppose you have a string that is 'ab{100}\0' and you wanted to remove all of the bs, you'd end up with 'a\0b{99}\0' in memory correct?
This is the source of the notorious "fgets" bug/hack/exploit.
This is not the time or place for a tutorial on C strings and memory management, but suffice to say that some people find it horrible, some people find it easy and obvious. It stems from C being a sort of macro-assembler with a simplistic type system glued on top of it.
ADDED IN EDIT: I don't know why you got down-voted - it's a reasonable question from someone who hasn't done C. I've up-voted you to get you back to "1".
Interesting, when I solved the problem originally on my own, I got to the exact same solution just with different variable names and braces. I suspect that this is probably the most common way to solve it.
Yeah, I had almost exactly the same code. I'm sure most people did too. The only other "obvious" algorithm is the n^2 one.
As in the article, I started simple and condensed to the version that I actually submitted. In hindsight, I wonder if that is the best approach when answering an interview question via email. In person, there's obvious benefit to walking through optimization (of all sorts, including visual), but if all the other party sees is the final version, they lose out on that demonstration of the process. If you were to receive just the more condensed version from an interviewee, would that be a benefit or detriment to the person? Does it make sense to send an analysis, or is that just risking overwhelming the interviewer?
I've asked for non-specific code samples in interviews before and that did serve to weed out an applicant once, but only because they sent on very easily searched for code (public API example code from a big developer). Asking for any sort of code example or coding example from an interviewer who isn't in the room always introduces the opportunity for cheating. Getting an analysis (I started here and ended up here) would probably help assuage my suspicions.
hmm, is it normal to assume all strings in C are \0 terminated? What are the memory usage implications for that? I won't pretend to know C but suppose you have a string that is 'ab{100}\0' and you wanted to remove all of the bs, you'd end up with 'a\0b{99}\0' in memory correct?
Memory management is between you, malloc() and free().
Assuming this were malloc()d memory, if you wanted to free up the unused bytes, you'd probably:
char *condensed = strdup(z_terminated);
if (condensed)
free(z_terminated);
else
// out of memory1) In TFA, s/cersion/version/, but that's an amusing typo. :-) 2) Initializing inside the for loop requires C99; is that to be considered idiomatic? I didn't think so. I'll be curious how many submissions were either identical to your suggested idiomatic solution or its K&R equiv: https://gist.github.com/3f4daf24595788258a01 :-)
1) In TFA, s/cersion/version/,
but that's an amusing typo.
:-)
I'm nowhere near an experience C coder, but doesn't the in place part mean that you don't create any additional variables or strings and just modify z_terminated? Is that even possible? This is an honest question, because the solution is obvious this way, but a bit harder if you can't create additional variables.
Because the resulting string will only be shorter (never longer), this works. You simply keep track of where you're copying to and where you're copying from, and move character by character until you reach the end. The resulting string may have extra stuff at the end, but since it's null terminated the standard C string functions will not see that cruft as they will stop at the first null.
void remove_char(char *s ,char c)
{
int from = -1;
int to = -1;
do {
from++; to++;
while (s[from] == c) from ++;
s[to] = s[from];
} while (s[from] != '\0');
}