c++ - 错误 : redefinition of 'class TextDocsCmpr'

Question

对不起!我有另一个问题。这是我试图解决的第一个最终错误。

我在头文件 PlagiarismDetector.h 的类定义中遇到错误:

#include <vector>  // std::vector
#include <string> // std::string
#include <fstream> // std::ifstream
#include <set> // std::set

class TextDocsCmpr { 

public: 
    TextDocsCmpr(); 
    ~TextDocsCmpr(); 
    void addFile(std::string); 
    void setThreshold(double); 

private:
    std::vector<std::string> files_vec; 
    std::vector<std::string> get_file_sntncs(std::fstream&);
    std::vector<std::string> get_sntnc_wrds(const std::string&);
    double sntnc_smlrty_qtnt(std::vector<std::string>, std::vector<std::string>);
    static std::set<char> LETTERS_SET;
    double sntnc_smlrty_thrshld; 
    static const double SNTNC_SMLRTY_THRSHLD_DEFAULT = 0.5;         
};

我不明白为什么它说我正在尝试重新定义它。对应的cpp文件为:

#include "PlagiarismDetector.h"


#include <iostream> // std::cout, std::endl
#include <algorithm> // std::swap
#include <map> // std::map

// ------------------------------------ TextDocsCmpr class member functions -----------------------------------------

// ---------- Public functions ------------

// Default constructor
TextDocsCmpr::TextDocsCmpr() { 
    // Set the sentence similarity threshold to its default value
    sntnc_smlrty_thrshld = SNTNC_SMLRTY_THRSHLD_DEFAULT;
    // Add all the characters of LETTERS_ARR to LETTERS_SET
    const char LETTERS_ARR[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
                                'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D',
                                'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 
                                'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '\'', '.'}; 
    for (int i = 0; i < sizeof(LETTERS_ARR)/sizeof(char); ++i)
        LETTERS_SET.insert(LETTERS_ARR[i]);
}


// Trivial destructor
TextDocsCmpr::~TextDocsCmpr() {}

// Add file to files_vec (if file is found)
void TextDocsCmpr::addFile(std::string filename) { 
        files_vec.push_back(filename);
} 

// Sets the sentence comparison threshold value
void TextDocsCmpr::setThreshold(double t) { 
    if (t < 0 || t > 1) {
        // Print error for now. Will change to an error window later.
        std::cout << "Threshold not changed. Must be bewteen 0 and 1 inclusive" << std::endl;
    } else { 
        sntnc_smlrty_thrshld = t; 
    }
}


// ---------- Private functions --------------

// Extract sentences from Plain Text file 
std::vector<std::string> TextDocsCmpr::get_file_sntncs(std::fstream& file) { 
    // The sentences will be stored in a vector of strings, strvec:
    std::vector<std::string> strvec; 
    // Print out error if the file could not be found: 
    if(file.fail()) {
        std::cout << "Could not find the file. :( " << std::endl;
        // Otherwise, proceed to add the sentences to strvec:
    } else { 
        char curchar;
        std::string cursentence;
        /* While we haven't reached the end of the file, add the current character to the 
         string representing the current sentence. If that current character is a period, 
         then we know we've reached the end of a sentence if the next character is a space,  
         a quotation mark (to denote the end of a quoted sentence), a new line character or
         if there is no next character; and we must then add the current sentence to strvec. */
        while (file >> std::noskipws >> curchar) { 
            cursentence.push_back(curchar);
            if (curchar == '.') {
                if (file >> std::noskipws >> curchar) { 
                    if (curchar == ' ' || curchar == '"' || curchar == '\n') {
                        strvec.push_back(cursentence);
                        cursentence.clear();
                    } else { 
                        cursentence.push_back(curchar);
                    }
                } else { 
                    strvec.push_back(cursentence);
                    cursentence.clear();
                }

            }

        }

    }
    return strvec; 
} 

std::vector<std::string> TextDocsCmpr::get_sntnc_wrds(const std::string& S) { 
    // The words of the sentence will be stored as a vector of strings and returned.
    std::vector<std::string> retvec;
    std::string::const_iterator it = S.begin(); 
    while (it != S.end()) { 
        if (LETTERS_SET.count(*it) == 1) { 
            /* We've found a letter. Now let us place all the consecutive letters
             into a string which will be added to our vector of strings, retvec. */
            std::string str(1,*it);
            int k(0);
            while (((it+k+1) != S.end()) && (LETTERS_SET.count(*(it+k+1)) == 1)) {  
                str.push_back(*(it + (++k)));
            }
            retvec.push_back(str);
            it += (k+1);
        }
        else { 
            // Or if we didn't find a letter, advance the iterator the unit. 
            ++it;
        }
    }
    return retvec;
} 

double TextDocsCmpr::sntnc_smlrty_qtnt(std::vector<std::string> S1, std::vector<std::string> S2) {
    // Force s1 to be the smaller sentence.
    if (S1.size() > S2.size())
        swap(S1, S2);
    // Add all the words of s1 to a set.
    std::set<std::string> wordset; 
    for (std::vector<std::string>::const_iterator it = S1.begin(); it != S1.end(); ++it) 
        wordset.insert(*it);
    // Save the number of unique words in s1.
    int oldsize = wordset.size(); 
    // Add the words of s2 to the set.
    for (std::vector<std::string>::const_iterator it = S2.begin(); it != S2.end(); ++it) 
        wordset.insert(*it);
    /* The difference between oldsize and the current size of wordset is the number of words in
     s2 which are not in s1. Therefore the proportion of words of s1 contained in s2 is oldsize/wordset.size(). 
     This is the sentence similarity quotient which is returned. */
    return (double)oldsize/(double)wordset.size();
}

// ----------------------------------------------------------------------------------------------------------

Answer 1

您可能在单个源文件中多次包含 PlagiarismDetector.h，可能间接通过另一个头文件。

为了防止这种情况，您应该使用 include guards .