I need help fixing some errors.

[Mediamessiah]

Basically I have an assignment to debug this code and allow it to run, my problem is I can't tell what is wrong based on the errors I'm receiving, so I'm completely lost on what to do. I really dont understand the "no matching function for call to..." error the most. In general I could use some help and explanations. The main area its telling me I have errors at are at lines 73 and 77, from what I understand

/*
        calculator08buggy.cpp

        Helpful comments removed.

        We have inserted 3 bugs that the compiler will catch and 3 that it won't
*/

#include "std_lib_facilities.h"

struct Token {
        char kind;
        double value;
        string name;
        Token(char ch) :kind(ch), value(0) { }
        Token(char ch, double val) : kind (ch), value(val) { }
};

class Token_stream {
        bool full;
        Token buffer;
public:
        Token_stream() :full(0), buffer(0) { }
        Token get();
        void unget(Token t) { buffer=t; full=true;}

        void ignore(char);
};

const char let = 'L';
const char quit = 'Q';
const char print = ';';
const char number = '8';
const char name = 'a';

Token Token_stream::get()
{
        if(full) { full=false; return buffer; }
        char ch;
        cin>>ch;
        switch (ch) {
        case '(':
        case ')':
        case '+':
        case '-':
        case '*':
        case '/':
        case '%':
        case ';':
        case '=':
                return Token(ch);
        case '.':
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
        {
                cin.unget();
                double val;
                cin>>val;
                return Token(number,val);
        }
        default:
                if(isalpha(ch)) {
                        string s;
                        s+=ch;
                        while(cin.get(ch)&&(isalpha(ch)|| isdigit(ch))) s=ch;
                        cin.unget();
                        if(s=="let") return Token(let);
                        if(s=="quit") return Token(name);
                        return Token(name,s);
                        }
                        error("Bad token");
                }
}
void Token_stream::ignore(char c)
{
        if(full && c==buffer.kind) {
                full = false;
                return;
        }
        full = false;

        char ch;
        while(cin>>ch)
                if(ch==c) return;
}


struct Variable {
        string name;
        double value;
        Variable(string n, double v) :name(n), value(v) { }
};

vector<Variable>names;

double get_value(string s)
{
        for(int i = 0; i<names.size(); ++i)
                if(names[i].name ==s) return names[i].value;
        error("get: undefined name ",s);
}

void set_value(string s, double d)
{
        for(int i=0; i<=names.size(); ++i)
                if(names[i].name==s) {
                        names[i].value = d;
                        return;
                }
        error("set: undefined name ",s);
}

bool is_declared(string s)
{
        for(int i =0; i<names.size();++i)
                if(names[i].name==s)return true;
        return false;
}

Token_stream ts;

double expression();

double primary()
{
        Token t=ts.get();
        switch(t.kind) {
        case '(':
        {       double d=expression();
                t=ts.get();
                if(t.kind!= ')') error("'(' expected");
        }
        case '-':
                return - primary();
        case number:
                return t.value;
        case name:
                return get_value(t.name);
        default:
                error("primary expected");
        }
}

double term()
{
        double left = primary();
        while(true) {
                Token t = ts.get();
                switch(t.kind) {
                case '*': {
                        left *= primary();
                        break;
                }
                case '/':
                {       double d = primary();
                        if(d==0) error("divide by zero");
                        left /= d;
                        break;
                }
                default:
                        ts.unget(t);
                        return left;
                }
        }
}

double expression()
{
        double left = term();
        while(true) {
                Token t = ts.get();
                switch(t.kind) {
                case '+':
                        left += term();
                        break;
                case '-':
                        left -= term();
                        break;
                default:
                        ts.unget(t);
                        return left;
                }
        }
}

double declaration()
{
        Token t = ts.get();
        if(t.kind != 'a') error ("name expected in declaration");
        string name = t.name;
        if(is_declared(name)) error(name, " declared twice");
        Token t2 = ts.get();
        if(t2.kind != '=') error("= missing in declaration of ", name);
        double d = expression();
        names.push_back(Variable(name,d));
        return d;
}

double statement()
{
        Token t = ts.get();
        switch(t.kind) {
        case let:
                return declaration();
        default:
                ts.unget(t);
                return expression();
        }
}

void clean_up_mess()
{
        ts.ignore(print);
}

const string prompt = "> ";
const string result = "= ";

void calculate()
{
        while(true) try {
                cout<< prompt;
                Token t = ts.get();
                while(t.kind==print) t=ts.get();
                if(t.kind==quit)return;
                ts.unget(t);
                cout<<result<<statement()<<endl;
        }
        catch(runtime_error& e) {
                cerr<<e.what()<<endl;
                clean_up_mess();
        }
}

int main()

        try{
                calculate();
                return 0;
        }
        catch (exception& e) {
                cerr<<"exception: "<<e.what()<<endl;
                char c;
                while(cin>>c&& c!=';');
                return 1;
        }
        catch(...) {
                cerr<<"exception\n";
                char c;
                while(cin>>c && c!=';');
                return 2;
        }

errors are as following:
hw3.cpp: In member function `Token Token_stream::get()':
hw3.cpp:77: error: no matching function for call to `Token::Token(const char&, String&)'
hw3.cpp:38: note: candidates are: Token::Token(const Token&)
hw3.cpp:16: note: Token::Token(char, double)
hw3.cpp:15: note: Token::Token(char)
std_lib_facilities.h: In constructor `String::String(S) [with S = char]':
hw3.cpp:73: instantiated from here
std_lib_facilities.h:106: error: invalid conversion from `char' to `const char*'
std_lib_facilities.h:106: error: initializing argument 1 of `std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]'

[Zhuge]

On line 77 you are trying to call the Token constructor with a const char& and a String& as parameters. You have no constructor defined that takes those arguments.

[Mediamessiah]

so how do I fix that

[Zhuge]

You can either create a constructor that takes those arguments or do something else on that line instead. What are you trying to accomplish there?

[Mediamessiah]

just to get it to compile