Необходимо проверить синтаксис для доступа к спискам, картам, структурам и другим контейнерам

Question

Это часть моей первой в истории программы на C++, и я очень не уверен в синтаксисе, который я использовал. Ищете исправления и предложения по улучшению кода.

Это моя структура, содержащая 3 карты:

typedef struct {  
std::map<std::string, int> firstCounts;  
std::map<std::string, int> pairCounts;  
std::map<std::string, std::list<std::string>> follows;  
} LanguageModel; 

Эти функции, которые должны работать с этим LanguageModel структуры:

using namespace std;  

string buildPair(string s1, string s2) {  
    string s3;  
    s3 = s1 + " " + s2;  
    return s3;  
} 

LanguageModel countSequence(LanguageModel &model, vector<string> &Seq) {  
    //append "<start>" and "<end>" to the vector of strings  
    vector<string>::iterator v = Seq.begin();  
    Seq.push_front("<START>");  
    v = Seq.end();  
    Seq.push_end("<END">);  
    v = Seq.begin();  

    //create word pairs  
    vector<string> pairs;  
    for (int n = 0; n <= Seq.size(); n++) {  
    pairs.at(n) = buildPair(Seq[n], Seq[n+1]);  
    }  

    //feed each word to map 1 with number of times it was seen  
    for (int m = 0; m <= Seq.size(); m++) {  
    ++model.firstCounts[Seq[m]];  
    model.firstCounts[Seq[m]] = count(Seq.begin(), Seq.end(), Seq[m]);  
    } 


    //feed each word pair and the number of times it was seen  
    for (int k = 0; k <= Seq.size(); k++) {  
    ++model.pairCounts[Seq[k]];  
    model.pairCounts[Seq[k]] = count(Seq.begin(), Seq.end(), Seq[m]);  
    } 

    //feed each unique first word in a word pair and the second words in the pairs 
    for (int l = 0; l <= Seq.size(); l++) {  
    istringstream iss(pairs[l]);  
    string sub;  
     iss >> sub;  
    string sub2;  
     iss >> sub2; 

     if (Seq[l] = sub) {  
      ++model.follows[sub];  
      model.follows[sub].push_back(sub2);  
     }   

    } 

return model; 
} 


string genNext(LanguageModel &model2, string &testWord, int Number) { 

    //use results of countSequence 

    return model2.follows[testWord][Number]; 

} 

код еще не компилируется, конечно ,

Эти ошибки я получаю:

LangModel.h:28:1: error: ‘string’ does not name a type 
string buildPair(std::string s1, std::string s2); 
^ 
LangModel.h:30:63: error: ‘string’ was not declared in this scope 
LanguageModel countSequence(LanguageModel &model, std::vector<string> &Seq); 
                  ^
LangModel.h:30:63: note: suggested alternative: 
In file included from /usr/include/c++/4.8/iosfwd:39:0, 
       from /usr/include/c++/4.8/ios:38, 
       from /usr/include/c++/4.8/ostream:38, 
       from /usr/include/c++/4.8/iostream:39, 
       from LangModel.h:13, 
       from hw5.cpp:10: 
/usr/include/c++/4.8/bits/stringfwd.h:62:33: note: ‘std::string’ 
    typedef basic_string<char> string; 
           ^
In file included from hw5.cpp:10:0: 
LangModel.h:30:69: error: template argument 1 is invalid 
LanguageModel countSequence(LanguageModel &model, std::vector<string> &Seq); 
                    ^
LangModel.h:30:69: error: template argument 2 is invalid 
LangModel.h:32:1: error: ‘string’ does not name a type 
string genNext(LanguageModel &model2, std::string &testWord, int Number); 
^ 
hw5.cpp: In function ‘int main()’: 
hw5.cpp:34:1: error: expected ‘}’ at end of input 

Обновление: Исправлены ошибки выше. Теперь получаю следующее:

LangModel.cpp: In function ‘LanguageModel countSequence(LanguageModel&, std::vector<std::basic_string<char> >&)’: 
LangModel.cpp:37:6: error: ‘class std::vector<std::basic_string<char> >’ has no member named ‘push_front’ 
    Seq.push_front("<START>"); 
    ^
LangModel.cpp:39:6: error: ‘class std::vector<std::basic_string<char> >’ has no member named ‘push_end’ 
    Seq.push_end("<END">); 
    ^
LangModel.cpp:39:22: error: expected primary-expression before ‘)’ token 
    Seq.push_end("<END">); 
        ^
LangModel.cpp:44:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] 
    for (int n = 0; n <= Seq.size(); n++) { 
           ^
LangModel.cpp:49:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] 
    for (int m = 0; m <= Seq.size(); m++) { 
           ^
LangModel.cpp:55:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] 
    for (int k = 0; k <= Seq.size(); k++) { 
           ^
LangModel.cpp:57:67: error: ‘m’ was not declared in this scope 
    model.pairCounts[Seq[k]] = count(Seq.begin(), Seq.end(), Seq[m]); 
                   ^
LangModel.cpp:61:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] 
    for (int l = 0; l <= Seq.size(); l++) { 
           ^
LangModel.cpp:62:20: error: variable ‘std::istringstream iss’ has initializer but incomplete type 
    istringstream iss(pairs[l]); 
        ^
LangModel.cpp:68:25: error: could not convert ‘(&(& Seq)->std::vector<_Tp, _Alloc>::operator[]<std::basic_string<char>, std::allocator<std::basic_string<char> > >(((std::vector<std::basic_string<char> >::size_type)l)))->std::basic_string<_CharT, _Traits, _Alloc>::operator=<char, std::char_traits<char>, std::allocator<char> >((*(const std::basic_string<char>*)(& sub)))’ from ‘std::basic_string<char>’ to ‘bool’ 
     if (Seq[l] = sub) { 
         ^
LangModel.cpp:69:10: error: no match for ‘operator++’ (operand type is ‘std::map<std::basic_string<char>, std::list<std::basic_string<char> > >::mapped_type {aka std::list<std::basic_string<char> >}’) 
      ++model.follows[sub]; 
     ^
LangModel.cpp: In function ‘std::string genNext(LanguageModel&, std::string&, int)’: 
LangModel.cpp:80:33: error: no match for ‘operator[]’ (operand types are ‘std::map<std::basic_string<char>, std::list<std::basic_string<char> > >::mapped_type {aka std::list<std::basic_string<char> >}’ and ‘int’) 
    return model2.follows[testWord][Number]; 
           ^
LangModel.cpp:81:1: warning: control reaches end of non-void function [-Wreturn-type] 
} 
^ 

Исправлено большинство ошибок выше. Это те, которые остались. Я уверен, что все они связаны с синтаксисом, но не уверены, как их исправить.

LangModel.cpp:69:25: error: could not convert ‘(&(& Seq)->std::vector<_Tp, _Alloc>::operator[]<std::basic_string<char>, std::allocator<std::basic_string<char> > >(((std::vector<std::basic_string<char> >::size_type)l)))->std::basic_string<_CharT, _Traits, _Alloc>::operator=<char, std::char_traits<char>, std::allocator<char> >((*(const std::basic_string<char>*)(& sub)))’ from ‘std::basic_string<char>’ to ‘bool’ 
     if (Seq[l] = sub) { 
         ^
LangModel.cpp:70:10: error: no match for ‘operator++’ (operand type is ‘std::map<std::basic_string<char>, std::list<std::basic_string<char> > >::mapped_type {aka std::list<std::basic_string<char> >}’) 
      ++model.follows[sub]; 
     ^
LangModel.cpp: In function ‘std::string genNext(LanguageModel&, std::string&, int)’: 
LangModel.cpp:81:33: error: no match for ‘operator[]’ (operand types are ‘std::map<std::basic_string<char>, std::list<std::basic_string<char> > >::mapped_type {aka std::list<std::basic_string<char> >}’ and ‘int’) 
    return model2.follows[testWord][Number]; 

Answer 1

Первая ошибка, которую вы получаете является:

LangModel.h:28:1: error: ‘string’ does not name a type 
string buildPair(std::string s1, std::string s2); 
^ 

Это означает, что string не известно компилятором. Вам нужно, в верхней части вашей программы, добавьте:

#include <string> 

Я вижу, у вас также есть using namespace std;. Хотя это работает для небольших программ, см. Why is “using namespace std;” considered bad practice?. Было бы лучше удалить using namespace std; и использовать std::string вместо string.

Answer 2

1) Вы, вероятно, хотите двойной равно здесь

if (Seq[l] = sub) 

должен выглядеть

if (Seq[l] == sub) 

2) «следует» отображает строку в списке, а компилятор говорит вам, что вы не можете увеличивать список.

++model.follows[sub];