C ++逐字读取文件，没有任何符号

Question

I want to read word by word from a text file. Here's my code in C++:

int main(int argc, const char * argv[]) {
    // insert code here...

    ifstream file("./wordCount.txt");
    string word;
    while(file >> word){
        cout<<word<<endl;
    }

    return 0;
}

The text file contains the sentence:

I don't have power, but he has power.

Here's the result I get:

I
don\241\257t
have
power,
but
he
has
power.

Can you tell me how to get the result like the below format:

I
don't
have
power
but
he
has
power

Thanks.

Answer 1

I understand that you're looking for getting rid of the punctuation.

Unfortunately, extracting strings from a stream looks only for spaces as separator. So "don't" or "Hello,world" would be read as one word, and "don' t" or "Hello, world" as two words.

The alternative, is to read the text line by line, and use string::find_first_of() to jump from separator to separator:

string separator{" \t\r\n,.!?;:"};
string line; 
string word;
while(getline (cin, line)){  // read line by line 
    size_t e,s=0;            // s = offset of next word, e = end of next word 
    do {
        s = line.find_first_not_of(separator,s);  // skip leading separators
        if (s==string::npos)                  // stop if no word left
            break;
        e=line.find_first_of(separator, s);   // find next separator 
        string word(line.substr(s,e-s));      // construct the word
        cout<<word<<endl;
        s=e+1;                                // position after the separator
    } while (e!=string::npos);                // loop if end of line not reached
}

Online demo

Answer 2

The code below, gets rid of punctuation, except of the apostrophe:

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>

using namespace std;

int main(int argc, const char * argv[]) {
    ifstream file("wordCount.txt");
    string word;
    while(file >> word) {
        for (auto c : word)
            if (ispunct(c) && c != '`')
                word.erase(word.find_first_of(c));
        cout << word << endl;
    }

    return 0;
}

should produce the desired output:

Georgioss-MacBook-Pro:~ gsamaras$ g++ -Wall -std=c++0x main.cpp 
Georgioss-MacBook-Pro:~ gsamaras$ ./a.out 
I
don`t
have
power
but
he
has
power

For the problem with some characters, I encourage you to check the encoding of the file, so try doing (as explained here ):

file -I wordCount.txt 
wordCount.txt: text/plain; charset=us-ascii

which is what worked for me. Or simply open a text editor and make sure the characters are valid.

Answer 3

To ease debug, I replace the file with std::istringstream.

• easy to add additional test input
• input is thus documented, and repeatable.

I also added a bool (class data attribute) to simplify enable/disable of additional diagnostic information. (m_dbg)

#include <algorithm>
#include <chrono>
// 'compressed' chrono access --------------vvvvvvv
typedef std::chrono::high_resolution_clock  HRClk_t; // std-chrono-hi-res-clk
typedef HRClk_t::time_point                 Time_t;  // std-chrono-hi-res-clk-time-point
typedef std::chrono::microseconds           MS_t;    // std-chrono-milliseconds
typedef std::chrono::microseconds           US_t;    // std-chrono-microseconds
typedef std::chrono::nanoseconds            NS_t;    // std-chrono-nanoseconds
using   namespace std::chrono_literals;          // support suffixes like 100ms, 2s, 30us

#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>
#include <vector>


class T496_t
{
   std::array<char, 256>     m_keep;
   std::vector<std::string>  m_wordVec;
   bool                      m_dbg = false;

public:

   T496_t()
      {
         for (uint i=0; i<256; ++i)
            m_keep[i] = static_cast<char>(i);
         m_keep[uint(',')] = 0;
         m_keep[uint('.')] = 0;
      }

   ~T496_t() = default;

   int exec()
      {
         std::istringstream file(
            "Hello\n"
            "I don't have power, but he has power.\n"
            "I don't  have power , but he has power.\n"
            ); //ifstream file("./wordCount.txt");

         uint lineCount = 1;
         while(1)
         {
            std::string line;
            (void)std::getline(file, line);
            if(file.eof())
            {
               ltrim(line);
               if(0 != line.size())
                  if(m_dbg) std::cout << __LINE__ << "  tail: " << line << std::endl;
               break;
            }

            if(m_dbg) std::cout << "\n  line " << lineCount++ << " :  '"
                                << line << "'\n  " << std::setfill('-')
                                << std::setw(static_cast<int>(line.size())+12)
                                << "-" << std::setfill(' ');
            std::cout << '\n';


            size_t sz = line.size();
            if(0 == sz)
               continue;     // ignore empty lines

            extractWordsFrom(line); // extract words

            if(file.eof()) break;
         }
         return(0);
      }

private: // methods

   void extractWordsFrom(std::string& unfiltered)
      {
         std::string line; // filtered
         filter(unfiltered, line);

         if(0 == line.size()) {
            if(m_dbg) std::cout << "  empty line" << std::endl; return;
         }

         size_t indx1 = 0;
         do {
            while(isspace(line[indx1])) { indx1 += 1; } // skip leading spaces

            size_t indx2 = line.find(" ", indx1);
            if(std::string::npos == indx2)
            {
               m_wordVec.push_back(line.substr(indx1));
               if(m_dbg) std::cout << "  word(" << std::setw(3) << indx1 << ", eoln): ";
               std::cout << "  " << m_wordVec.back() << std::endl;
               break;
            }

            m_wordVec.push_back(line.substr(indx1, indx2-indx1));
            if(m_dbg) std::cout << "  word(" << std::setw(3) << indx1 << ","
                                << std::setw(3) << indx2 << "): ";
            std::cout << "  " << m_wordVec.back() << std::endl;
            indx1 = indx2+1;

         }while(1);
      }

   void filter(std::string& unfiltered, std::string& line)
      {
         ltrim(unfiltered); // remove leading blanks

         for(uint i=0; i<unfiltered.size(); ++i) // transfer all chars
            if(m_keep[unfiltered[i]])            // exception check
               line.push_back(unfiltered[i]);
      }


   // trim from start
   void  ltrim(std::string &s) {
      s.erase(s.begin(),
              std::find_if(s.begin(), s.end(),
                           std::not1(std::ptr_fun<int, int>(std::isspace)) ));
   }
   // trim from end
   void rtrim(std::string &s) {
      s.erase(std::find_if(s.rbegin(), s.rend(),
                           std::not1(std::ptr_fun<int, int>(std::isspace))).base(),s.end());
   }
   // trim from both ends
   void  lrtrim(std::string &s) { rtrim(s); ltrim(s); }

}; // class T496_t


int main(int /*argc*/, char** /*argv[]*/)
{
  setlocale(LC_ALL, "");
  std::ios::sync_with_stdio(false);

  Time_t start_us = HRClk_t::now();

  int retVal = -1;
  {
     T496_t   t496;
     retVal = t496.exec();
  }

  auto  duration_us = std::chrono::duration_cast<US_t>(HRClk_t::now() - start_us);
  std::cout << "\n\n  FINI   " << duration_us.count() << " us" << std::endl;
  return(retVal);

}

---

   // desired output:
   // I
   // don't
   // have
   // power
   // but
   // he
   // has
   // power

---

Output from this code:

  Hello

  I
  don't
  have
  power
  but
  he
  has
  power

  I
  don't
  have
  power
  but
  he
  has
  power

---

Output with m_dbg=true

  line 1 :  'Hello'
  -----------------
  word(  0, eoln):   Hello

  line 2 :  'I don't have power, but he has power.'
  -------------------------------------------------
  word(  0,  1):   I
  word(  2,  7):   don't
  word(  8, 12):   have
  word( 13, 18):   power
  word( 19, 22):   but
  word( 23, 25):   he
  word( 26, 29):   has
  word( 30, eoln):   power

  line 3 :  'I don't  have power , but he has power.'
  ---------------------------------------------------
  word(  0,  1):   I
  word(  2,  7):   don't
  word(  9, 13):   have
  word( 14, 19):   power
  word( 21, 24):   but
  word( 25, 27):   he
  word( 28, 31):   has
  word( 32, eoln):   power


  FINI   215 us

Answer 4

A simple approach is first to filter the string. Remove any punctuation except apostrophe (ie ' ) and replace them with white-space for further manipulation (ie to take advantage of some built-in functions).

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <sstream>
#include <iterator>

using namespace std;

bool isOk(char c)
{
    if ( ispunct(c) )
        if ( c == '\'' )
            return false;

    return ispunct(c);
}

int main()
{
    ifstream file("data.txt");
    string word;

    while(file >> word){
        std::replace_if(word.begin(), word.end(), isOk, ' ');
        istringstream ss(word);
        copy(istream_iterator<string>(ss), istream_iterator<string>(), ostream_iterator<string>(cout, "\n"));
    }

    return 0;
}

The output is

I
don't
have
power
but
he
has
power