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bad words filter?

Started by orbitafx Nov 7, 2009 at 8:45 AM 5 replies 1.3k views

Original Post

Nov 7, 2009 at 8:45 AM

hello all, first post... I am having a problem with an example in a book i'm reading (programming principles and practice - stroustrup) I want to compare 2 vectors of words in a loop... vectorwords[2]; words[0]="dog"; words[1]="cat"; words[2]="human"; and vectorbadwords[2]; badwords[0]="hell"; badwords[1]="damn"; so i'll loop through the values if i find a bad word ill replace it with "bad word" if not, print words... I tried using a nested loop but it didn't quite work out as planned... If you want me to post the code I had, I will when I wake up...

assainator

Nov 7, 2009 at 9:10 AM

something like this?

vector<string>words[3]; //make a vector for 3 words and add the wordswords[0]="dog";words[1]="cat";words[2]="human";vector<string>badwords[2];.//make a vector 2 two words and add the bad wordsbadwords[0]="hell";badwords[1]="damn";for(unsigned int i = 0; i < words.size(); i++) //loop through all words in the  words vector{  bool foundBadWord = false; //a boolean to see if we've found a bad word  for(unsigned int j = 0; j < badWords.size(); j++) //loop through all bad words in the bad words vector  {    if(words == badWords[j]) //if the word is bad change the boolean    {      foundBadWord = true;    }  }  if(foundBadWord == true) //if the word was a bad word print "bad word"  {    std::cout << "bad word" << std::endl;  }  else //else, print the word  {    std::cout << words;  }}

Hope it helps,
assainator

MadMax1992

Nov 7, 2009 at 9:12 AM

Allright, your problem in pseudocode:

loop through all the words    loop through all bad words        if word == badword            set isabadword-flag to true        endif    endloop    if isabadword-flag was set        print "badword"    else        print word    endifendloop

try to implement that and come back if you have any problems, I would like to see your code to see what you're doing wrong.

Edit: I got ninja'd...

mattd

Nov 7, 2009 at 9:39 AM

Don't forget to break after finding a matching bad word in your inner loop. There's no need to continuing searching after setting your is-bad-word flag.

Also, here's a more idiomatic C++ way, taking advantage of the STL:

#include <algorithm>for(int i = 0; i < words.size(); ++i)    if(std::find(badwords.begin(), badwords.end(), words) == badwords.end())        std::cout << words << " ";    else        std::cout << "[CENSORED!] ";

Also, you specify the initial size of a std::vector using its constructor, like this:
vector words(3);
You don't use square brackets for that.

Aaand.. you need to specify an initial size of 3 for words, not 2! :)

Zahlman

Nov 7, 2009 at 1:56 PM

When I had to do this for a real-world project, I concatenated the bad words together with '|', compiled the result as a regular expression, cached the compiled regular expression, and would then run it against whatever input (with a bit of filtering). Depending on your requirements, you might need \b or something on either side of each word in the regular expression.

OTOH, I was doing this in Python, where it's considerably easier to do something like that. :) But the point is that once compiled, a regular expression is much faster at this sort of thing, at least in the algorithmic-complexity sense.

stonemetal

Nov 7, 2009 at 2:30 PM

If you go the regular expression route be sure to check for word boundaries you don't want classic to get flagged accidentally.

orbitafx

Nov 7, 2009 at 10:20 PM

thanks for the help, this way I have a few ways to do it next time...

definitely learned something new, looks like the find() function is the best way, but also made me realize the use of booleans

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