在c ++中获取基本的文本处理器进行编译 [英] Getting basic text processor in c++ to compile
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问题描述
如主题中所述，我有麻烦获得一个基本的文本处理器编译。以下代码适用于基本部分。这意味着。当find_text（）和match（）函数被排除时，它获取一个文本文件并将其读入一个Document类，并使用print（）输出它。但是当我包括上面提到的功能，并尝试编译它给出大量的错误消息。
As stated in the subject i am in trouble getting a basic text processor to compile. The following code works in basic parts. That means. when find_text() and match() functions are excluded it gets a text file and reads it into a Document class and outputs it using print(). But when i include above mentioned functions and try to compile it gives large amount of error messages.
这段代码来自Stroustrup编程：使用c ++的实践和原理第20章。在练习中，我应该获取运行示例代码部分并继续编写match功能。任何人都可以指出代码中的错误？我使用Visual studio 2013和CTP 2013年11月编译器。
This code is from Stroustrup "Programming: practice and principles using c++" Chapter 20. In the exercises i should get sample code parts to run and continue writing a match() function. Can anyone point out the mistake in code? I am using Visual studio 2013 and a CTP November 2013 compiler.
#include <algorithm>
#include <string>
#include <vector>
#include <iostream>
#include<fstream>
#include<sstream>
#include <list>
using namespace std;
using Line = vector<char>; // a line is a vector of characters
//....................TEXT ITERATOR CLASS......................
class Text_iterator { // keep track of line and character position within a line
list<Line>::iterator ln;
Line::iterator pos;
public:
// start the iterator at line ll’s character position pp:
Text_iterator(list<Line>::iterator ll, Line::iterator pp)
:ln { ll }, pos { pp } { }
char& operator*() { return *pos; }
Text_iterator& operator++();
bool operator==(const Text_iterator& other) const {
return ln == other.ln && pos == other.pos;
}
bool operator!=(const Text_iterator& other) const {
return !(*this == other);
}
};
Text_iterator& Text_iterator::operator++() {
++pos; // proceed to next character
if (pos == (*ln).end()) {
++ln; // proceed to next line
pos = (*ln).begin(); // bad if ln==line.end(); so make sure it isn’t
}
return *this;
}
//....................DOCUMENT CLASS......................
struct Document {
list<Line> line; //doucument is a list of lines
Document() { line.push_back(Line { }); }
Text_iterator begin() // first character of first line
{
return Text_iterator(line.begin(), (*line.begin()).begin());
}
Text_iterator end() // one beyond the last character of the last line
{
auto last = line.end();
--last; // we know that the document is not empty
return Text_iterator(last, (*last).end());
}
};
istream& operator>>(istream& is, Document& d) {
for (char ch; is.get(ch);) {
d.line.back().push_back(ch); // add the character
if (ch == '\n')
d.line.push_back(Line { }); // add another line
}
if (d.line.back().size()) d.line.push_back(Line { }); // add final empty line
return is;
}
//....................HELPER FUNCTIONS......................
void erase_line(Document& d, int n) {
if (n < 0 || d.line.size() - 1 <= n) return;
auto p = d.line.begin();
advance(p, n);
d.line.erase(p);
}
void print(Document& d) {
for (auto p : d) cout << p;
// int the book sample code is different: "cout<<*p"` but the book code gives error of illegal transition. This would also need a comment
}
/*
bool match(Text_iterator first, Text_iterator last, const string& s) {
for (int i = 0; i < s.size(); ++i) {
if (*first == s[i]);
if (*first != s[i])return false;
}
return true;
}
Text_iterator find_txt(Text_iterator first, Text_iterator last, const string& s) {
if (s.size() == 0) return last; // can’t find an empty string
char first_char = s[0];
while (true) {
auto p = find(first, last, first_char);
if (p == last || match(p, last, s)) return p;
first = ++p; // look at the next character
}
}
*/
int main() {
string filename1 = "myDoc.txt";
ifstream stream { filename1 };
Document text1;
stream >> text1;
print(text1);
char ch; cin >> ch;
}
我得到的错误如下：
Error 6 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 371 1 text processing proov
Error 11 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 372 1 text processing proov
Error 16 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 373 1 text processing proov
Error 21 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 375 1 text processing proov
Error 26 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 376 1 text processing proov
Error 13 error C2868: 'std::iterator_traits<_InIt>::value_type' : illegal syntax for using-declaration; expected qualified-name c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 372 1 text processing proov
Error 28 error C2868: 'std::iterator_traits<_InIt>::reference' : illegal syntax for using-declaration; expected qualified-name c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 376 1 text processing proov
Error 23 error C2868: 'std::iterator_traits<_InIt>::pointer' : illegal syntax for using-declaration; expected qualified-name c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 375 1 text processing proov
Error 8 error C2868: 'std::iterator_traits<_InIt>::iterator_category' : illegal syntax for using-declaration; expected qualified-name c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 371 1 text processing proov
Error 18 error C2868: 'std::iterator_traits<_InIt>::difference_type' : illegal syntax for using-declaration; expected qualified-name c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 373 1 text processing proov
Error 29 error C2665: 'std::_Debug_range2' : none of the 2 overloads could convert all the argument types c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 584 1 text processing proov
Error 12 error C2602: 'std::iterator_traits<_InIt>::value_type' is not a member of a base class of 'std::iterator_traits<_InIt>' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 372 1 text processing proov
Error 27 error C2602: 'std::iterator_traits<_InIt>::reference' is not a member of a base class of 'std::iterator_traits<_InIt>' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 376 1 text processing proov
Error 22 error C2602: 'std::iterator_traits<_InIt>::pointer' is not a member of a base class of 'std::iterator_traits<_InIt>' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 375 1 text processing proov
Error 7 error C2602: 'std::iterator_traits<_InIt>::iterator_category' is not a member of a base class of 'std::iterator_traits<_InIt>' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 371 1 text processing proov
Error 17 error C2602: 'std::iterator_traits<_InIt>::difference_type' is not a member of a base class of 'std::iterator_traits<_InIt>' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 373 1 text processing proov
Error 10 error C2146: syntax error : missing ';' before identifier 'value_type' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 372 1 text processing proov
Error 25 error C2146: syntax error : missing ';' before identifier 'reference' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 376 1 text processing proov
Error 20 error C2146: syntax error : missing ';' before identifier 'pointer' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 375 1 text processing proov
Error 5 error C2146: syntax error : missing ';' before identifier 'iterator_category' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 371 1 text processing proov
Error 15 error C2146: syntax error : missing ';' before identifier 'difference_type' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 373 1 text processing proov
Error 9 error C2039: 'value_type' : is not a member of 'Text_iterator' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 372 1 text processing proov
Error 24 error C2039: 'reference' : is not a member of 'Text_iterator' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 376 1 text processing proov
Error 19 error C2039: 'pointer' : is not a member of 'Text_iterator' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 375 1 text processing proov
Error 4 error C2039: 'iterator_category' : is not a member of 'Text_iterator' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 371 1 text processing proov
Error 14 error C2039: 'difference_type' : is not a member of 'Text_iterator' c:\program files (x86)\microsoft visual studio 12.0\vc\include\xutility 373 1 text processing proov
推荐答案
当在标准库中调用函数时使用自定义迭代器，他们有一些期望。
When you use a custom iterator when calling a function in the standard library, they have some expectations.
我看到错误：
'value_type' : is not a member of 'Text_iterator'
'reference' : is not a member of 'Text_iterator'
'pointer' : is not a member of 'Text_iterator'
'iterator_category' : is not a member of 'Text_iterator'
'difference_type' : is not a member of 'Text_iterator'
查看 http://en.cppreference.com/w/cpp/iterator/iterator 来了解迭代器的期望。您可以通过从 std :: iterator 中导出 Text_iterator 来修复编译器问题。
Take a look at the http://en.cppreference.com/w/cpp/iterator/iterator to understand what's expected of an iterator. You can fix your compiler problems by deriving Text_iterator from std::iterator.
class Text_iterator : public std::iterator<std::input_iterator_tag, char> {
...
};
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