Question

我试图编写一个程序：

解析文本，删除预先指定的（标点符号）字符，并创建一个按字母顺序排列的字典，其中包含文本中已解析的单词，然后显示在屏幕上。来自 Bjarne Stroustup的C ++编程：原理与实践

这是我写的：

Chapter11Exercise7Execute.cpp

#include "stdAfx.h"
#include "Chapter11Exercise7.h"

const string endInput("x");

int main(){
try{
    // instantiate a PunctStream object and initialize it to: cin
    PunctStream ps(cin);
    // construct initial set of characters to be replaced with whitepace 
    ps.whitespace(",");
    // set case sensitivity
    ps.caseSensitive(false);

    string word;
    vector<string> dictionary;
    do{
        cout << "Type a word\n>>";
        cin >> word;

        createDictionary(ps, dictionary);
        printDictionary(dictionary);            
    }while(word != endInput);
 }catch(exception& e){
    cerr << e.what() << endl;
    getchar();
 }
 return 0;
 }

Chapter11Exercise7.h

#include "stdAfx.h"
#ifndef _Chapter11Exercise7_H
#define _Chapter11Exercise7_H

class PunctStream{
public:
    // constructors
    PunctStream(istream& is): source(is), sensitive(true){ }
    // member-functions
    // creates a set of characters to be searched and replaced with whitespace
    void whitespace(const string& s){white = s;}; 
    void addWhitespace(char c){white += c;};
    bool isWhitespace(char c);
    // set case sensitivity
    void caseSensitive(bool b){sensitive = b;};
    bool isCaseSensitive(){return sensitive;};
    // overwritten extraction operator
    PunctStream& operator>>(string& s);
    // operator that returns a bool value on success/failure of PunctStream object  
    operator bool();
private:
    // stream containing text to be parsed
    istream source;
    // stringstream containing a parsed text
    istringstream buffer;
    // case sensitivity 
    bool sensitive;
    // characters to be replaced with whitespace
   string white;
 };
 // Non-member functions
 void createDictionary(PunctStream& ps, vector<string>& d);
 void printDictionary(vector<string>& d);
 #include "Chapter11Exercise7V1.cpp"
 #endif

Chapter11Exercise7.cpp

 #include "Chapter11Exercise7.h"

 // Member functions definition
 bool PunctStream::isWhitespace(char c){
    for(size_t i; i < white.size(); i++) if (c == white[i]) return true;
   return false;
 }
 // Overwritten operators definition
 PunctStream& PunctStream::operator>>(string& s){
    while(!(buffer >> s)){
    // if buffer bad() or source not food => return PunctStream object
    // this is a pointe to the object in context
    if(buffer.bad() || !source.good()) return *this;
    buffer.clear();

    string line;
    // get a line from source
    getline(source, line);
    // replace "white" characters in "line"
    for(size_t i = 0; i < line.size(); ++i){
        if(isWhitespace(line[i])) line[i] = ' ';
        // if case sensitivity is set => convert to lowercase
        else if (!sensitive) line[i] = tolower(line[i]);
    }
    // initialize the stringstream buffer to "line"
    buffer.str(line);
  }
  return *this;
}

 PunctStream::operator bool(){
    // to return true: fail() and bas() should be unset, good()-set
    return !(source.fail() || source.bad()) && source.good();
 }
 // Non-member functions
 void createDictionary(PunctStream& ps, vector<string>& d){
   string word;
   while(ps >> word) d.push_back(word);

   sort(d.begin(), d.end());
 }

 void printDictionary(vector<string>& d){
   for(size_t i = 0; i < d.size(); ++i) cout << d[i] <<'\n';
 }

我得到的错误如下：

1>------ Build started: Project: bjarneStroustroupC, Configuration: Debug Win32 ------
1>  Chapter11Exercise7Execute.cpp
1>c:\program files (x86)\microsoft visual studio 10.0\vc\include\istream(860): error C2248: 'std::basic_ios<_Elem,_Traits>::basic_ios' : cannot access private member declared in class 'std::basic_ios<_Elem,_Traits>'
1>          with
1>          [
1>              _Elem=char,
1>              _Traits=std::char_traits<char>
1>          ]
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\ios(176) : see declaration of 'std::basic_ios<_Elem,_Traits>::basic_ios'
1>          with
1>          [
1>              _Elem=char,
1>              _Traits=std::char_traits<char>
1>          ]
1>          This diagnostic occurred in the compiler generated function 'std::basic_istream<_Elem,_Traits>::basic_istream(const std::basic_istream<_Elem,_Traits> &)'
1>          with
1>          [
1>              _Elem=char,
1>              _Traits=std::char_traits<char>
1>          ]
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

我已阅读错误消息，但它没有响铃。欢迎任何见解或建议！

Answer 1

如果您尝试复制istream对象，则会收到此错误消息，因为istream不可复制。我认为这具体发生在这里：

class PunctStream{
public:
   PunctStream(istream& is): source(is), sensitive(true){ }

private:
    istream source;
};

在这里，您尝试将source数据成员初始化为输入流参数is的副本，因此出错。

要解决此问题，请考虑将source更改为istream& - 对istream的引用 - 而不是具体的istream对象。

希望这有帮助！

自定义流对象错误？

1 个答案: