Source code not compiling...

Hi all,

I'm currently working through Programming Principles and Practise and the following code won't compile. I thought it may have been something I have done, but I have since downloaded the source code from Bjarne's site and it still wont compile:

Code:

---

//
// This is example code from Chapter 6.3.4 "Using tokens" of
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//

#include "../std_lib_facilities.h"

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

class Token {
public:
    char kind;        // what kind of token
    double value;    // for numbers: a value
    Token(char ch)    // make a Token from a char
        :kind(ch), value(0) { }   
    Token(char ch, double val)    // make a Token from a char and a double
        :kind(ch), value(val) { }
};

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

Token get_token();    // read a token from cin

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

vector<Token> tok;    // we'll put the tokens here

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

int main()
{
    while (cin) {
        Token t = get_token();
        tok.push_back(t);
    }
    // ...
    //Now we could find the multiply operation by a simple loop:

    for (int i = 0; i<tok.size(); ++i) {
        if (tok[i].kind=='*') {    // we found a multiply!
            double d = tok[i-1].value*tok[i+1].value;
            // now what?
        }
    }
}

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

---

The errors I get are:

1>c:\users\darren\documents\visual studio 2008\projects\accelerated c++\accelerated c++\calc3.cpp(39) : warning C4018: '<' : signed/unsigned mismatch
1>Linking...
1>LINK : warning LNK4076: invalid incremental status file 'C:\Users\Darren\Documents\Visual Studio 2008\Projects\Accelerated C++\Debug\Accelerated C++.ilk'; linking nonincrementally
1>Calc3.obj : error LNK2019: unresolved external symbol "class Token __cdecl get_token(void)" (?get_token@@YA?AVToken@@XZ) referenced in function _main
1>C:\Users\Darren\Documents\Visual Studio 2008\Projects\Accelerated C++\Debug\Accelerated C++.exe : fatal error LNK1120: 1 unresolved externals
1>Build log was saved at "file://c:\Users\Darren\Documents\Visual Studio 2008\Projects\Accelerated C++\Accelerated C++\Debug\BuildLog.htm"
1>Accelerated C++ - 2 error(s), 2 warning(s)

Any help would be appreciated.

Thanks.

Perhaps you are missing or somehow did not compile the file that contains the definition of the get_token() function.

Quote:

---

Originally Posted by laserlight

Perhaps you are missing or somehow did not compile the file that contains the definition of the get_token() function.

---

Hasn't that been declared by:

Token get_token();

According to the book this should compile?

Thanks.

Quote:

---

Originally Posted by darren78

Hasn't that been declared by:

Token get_token();

---

But, but it also has to be defined (implemented) somewhere.

Quote:

---

Originally Posted by darren78

According to the book this should compile?

---

And indeed the source file was compiled. What you have is a linker error.

So, would you say the error is the line:

Token get_token(); and that should have been where the function was defined?

No, that is not an error. It may be the case that the function is defined in another source file which you did not include in the project.

Sorted now thanks. The function was included later on.....