Alright, so, I was kind of messing around and I noticed that this:
Doesn't work...Code:#include <iostream> #include <cstring> using namespace std; int main() { char a = 'x'; char b[10] = "xxaxxaxa"; int matchcount = 0; int len = strlen(b); cout<<len<<endl; for (int c = 0; c == len; c++) { if (a == b[c]) matchcount++; } cout<<matchcount; cin.get(); return 0; }
matchcount returns 0 no matter what. Could somebody please enlighten me as to why it's not working?
think of for loops like a while loop, the condition needs to be true..
so while c < len do..
you had while c = len do.
I've just started learning c++, after years of other languages, so please correct me someone if i'm wrong... also a word of advice..Code:for (int c = 0; c < len; c++) { // dostuff }
to test anything I always declare a variableat the top of the page, and put cout << test++; everywhere to see where my logic stalls..Code:int test = 0;
Thanks
Last edited by cope; 06-06-2007 at 03:51 AM. Reason: added the end.
You set c to 0, first. Your condition then says "if c is equal to len" but it since it is not equal, the condition is not verified and the for loop isn't executed. Thus, matchcount isn't incremented.Code:for (int c = 0; c == len; c++)
Wolves, think this: "while this is true, loop and increment, if it's not don't."
Your method:
For (int c=0; c == x; ++c) // while (c==x) loop & increment c, else don't
// c != x at this point, no loop
Intended method:
For (int c=0; c < x; ++c) // while (c < x) loop & increment c, else don't
// c < x at this point, loop
or <= if you want c to tend to x, instead of x-1.
I see you said c==x which makes me believe you're trying to count up to 10 (the array size). Keep in mind that if you set an array of [n=]10 values, you do NOT need to loop to the number 10, you only have to go through 10 values, which is 0->9, we always start at 0, so all loops which involve arrays should be told to tend to n-1. You could say that the loop starts at 1 and go through 10, but then you'll read outside of the array bounds (array[9] is '10th' value), which if you insist on this case then you should do something like;
For (int c=1; c<10; ++c)
array[c-1];
I hope this example more clearly illustrates the issue and reasoning.
Last edited by simpleid; 06-06-2007 at 09:38 AM.
Schwoops, that's what I get for not using logic. Thanks all.
