How do you read a word in from a file in C++?

问题:

So I was feeling bored and decided I wanted to make a hangman game. I did an assignment like this back in high school when I first took C++. But this was before I even too geometry, so unfortunately I didn't do well in any way shape or form in it, and after the semester I trashed everything in a fit of rage.

I'm looking to make a txt document and just throw in a whole bunch of words (ie: test love hungery flummuxed discombobulated pie awkward you get the idea )

So here's my question: How do I get C++ to read a random word from the document?

I have a feeling #include<ctime> will be needed, as well as srand(time(0)); to get some kind of pseudorandom choice...but I haven't the foggiest on how to have a random word taken from a file...any suggestions?

Thanks ahead of time!

回答1:

Here's a rough sketch, assuming that the words are separated by whitespaces (space, tab, newline, etc):

vector<string> words;
ifstream in("words.txt");
while(in) {
  string word;
  in >> word;
  words.push_back(word);
}

string r=words[rand()%words.size()];

回答2:

The operator >> used on a string will read 1 (white) space separated word from a stream.

So the question is do you want to read the file each time you pick a word or do you want to load the file into memory and then pick up the word from a memory structure. Without more information I can only guess.

Pick a Word from a file:

// Note a an ifstream is also an istream. 
std::string pickWordFromAStream(std::istream& s,std::size_t pos)
{
    std::istream_iterator<std::string> iter(s);
    for(;pos;--pos)
    {    ++iter;
    }

    // This code assumes that pos is smaller or equal to
    // the number of words in the file
    return *iter;
}

Load a file into memory:

void loadStreamIntoVector(std::istream& s,std::vector<std::string> words)
{
    std::copy(std::istream_iterator<std::string>(s),
              std::istream_iterator<std::string>(),
              std::back_inserter(words)
             );
}

Generating a random number should be easy enough. Assuming you only want psudo-random.

回答3:

I would recommend creating a plain text file (.txt) in Notepad and using the standard C file APIs (fopen(), and fread()) to read from it. You can use fgets() to read each line one at a time.

Once you have your plain text file, just read each line into an array and then randomly choose an entry in the array using the method you've suggested above.