How to construct a parser for an input file

Question

can i please get some guidance to constructing a parser for an input file, I've been looking for a help for weeks, the assignment is already past due, I would just like to know how to do it.

The commented code is what I've tried, but i have a feeling it is more serious than that. I have a text file and I want to parse it to count the number of times that words appear in the document.

   Parser::Parser(string filename) {
   //ifstream.open(filename);

  // source (filename, fstream::in | fstream::out);

 }

You'll probably need to tell us about the format of the input file before we can give any really intelligent advice. — Jerry Coffin
– Jerry Coffin, Commented Apr 20, 2011 at 19:54
@Nikolai N Fetissov: I think a book about C++ would be more appropriate. — orlp
– orlp, Commented Apr 20, 2011 at 19:55
Are you having trouble parsing the string or reading the text file in? This will change the kinds of answers you receive. — Lunin
– Lunin, Commented Apr 20, 2011 at 19:56
all the words in the text file are in lower case, it is a a speech so many words, pauses and such — Technupe
– Technupe, Commented Apr 20, 2011 at 19:59

orlp · Accepted Answer · 2011-04-20 19:54:44Z

1

The commented code is what I've tried, but i have a feeling it is more serious than that.

I have a feeling you haven't tried a thing. So I am going to do the same.

Google is your friend.

answered Apr 20, 2011 at 19:54

orlp

119k39 gold badges226 silver badges324 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Loki Astari · Accepted Answer · 2011-04-20 21:10:27Z

0

To read a word:

std::ifstream  file("FileName");

std::string word;
file >> word; // reads one word from a file.


// Testing a word:
if (word == "Floccinaucinihilipilification")
{
     ++count;
}

// Count multiple words
std::map<std::string, int>   count;

// read a word
++count[word];

// To read many words from a file:

std::string word;
while(file >> word)
{
     // You have now read a word from a file
}

Note: That is a real word :-)
http://dictionary.reference.com/browse/floccinaucinihilipilification

edited Apr 20, 2011 at 21:10

answered Apr 20, 2011 at 19:59

Loki Astari

267k87 gold badges344 silver badges575 bronze badges

4 Comments

Technupe Over a year ago

so how do i make the parser read the whole file instead of just one word?

evnu Over a year ago

See stackoverflow.com/questions/625247/… for reading the whole file.

Loki Astari Over a year ago

I just followed that link. The accepted answer is wrong. Update my answer.

Loki Astari Over a year ago

@Benjamin Lindley: No. My friends and I have an on going bet (since university) to see who can use the word in everyday conversation (without forcing it).

Community · Accepted Answer · 2017-05-23 11:55:50Z

0

Take a look at the answers in How do you read a word in from a file in C++? . The easiest way is to use an ifstream and operator>> to read single words. You can then use a standard container like vector (as mentioned in the link above) or map<string, int> to remember the actual count.

edited May 23, 2017 at 11:55

CommunityBot

11 silver badge

answered Apr 20, 2011 at 19:55

evnu

6,7402 gold badges29 silver badges39 bronze badges

Collectives™ on Stack Overflow

How to construct a parser for an input file

3 Answers 3

Comments

4 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related