CODEWITHSUNDEEP
c++static
peugart
peugart

Reputation: 33

Calling a Static Method, Getting error: LNK2019

I'm having some troubles making a string utility class that has only static methods. Whenever I use a calling class to use a static method in my string utility class, it compiles with an LNK error, 2019. Any help would be much appreciated. .h is below,

#pragma once
#include <string>
#include "stdafx.h"
#include <iostream>
using namespace std;
static class StringUtil
{
public:
    static string Reverse(string);
   // bool Palindrome(string);
   // string PigLatin(string);
   // string ShortHand(string); 
private:
   // string CleanUp(string);
};

.cpp file is below,

   #include "StdAfx.h"
   #include "StringUtil.h"
   #include <iostream>

static string Reverse(string phrase)
{
    string nphrase = "";
    for(int i = phrase.length() - 1; i > 0; i--)
    {
        nphrase += phrase[i];
    }
    return nphrase;
}

and below is the calling class. 

#include "stdafx.h"
#include <iostream>
#include "StringUtil.h"

void main() 
{
    cout << "Reversed String: " << StringUtil::Reverse("I like computers!");
}

And when it runs, it shows

Error 5 error LNK2019: unresolved external symbol "public: static class std::basic_string,class std::allocator > __cdecl StringUtil::Reverse(class std::basic_string,class std::allocator >)" (?Reverse@StringUtil@@SA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V23@@Z) referenced in function "void __cdecl a10_StringUtil(void)" (?a10_StringUtil@@YAXXZ) H:\Visual Studio 2010\Projects\Object Oriented C++\Object Oriented C++\Object Oriented C++.obj Object Oriented C++

and

Error 6 error LNK1120: 1 unresolved externals H:\Visual Studio 2010\Projects\Object Oriented C++\Debug\Object Oriented C++.exe 1 1 Object Oriented C++

I feel like this is a very simple problem, but I'm used to programming in Java. I'm trying to teach myself how to code in c++ currently, hence my problem.

Upvotes: 3

Views: 4080

Answers (2)

Denis Kotov
Denis Kotov

Reputation: 882

First of all in C++ we do not have static classes:

#pragma once
#include <string>
#include "stdafx.h"
#include <iostream>
using namespace std;

class StringUtil
{
public:
    static string Reverse(string);
   // bool Palindrome(string);
   // string PigLatin(string);
   // string ShortHand(string); 
private:
   // string CleanUp(string);
};

Second you forgot the class name StringUtil (owner):

string StringUtil::Reverse(string phrase)
{
    string nphrase = "";
    for(int i = phrase.length() - 1; i >= 0; i--)
    {
        nphrase += phrase[i];
    }
    return nphrase;
}

I hope this helps you :)

Upvotes: 5

R Sahu
R Sahu

Reputation: 206567

static string Reverse(string phrase)
{
   ...
}

does not define the static member function of the class. It defines a file scoped non-member function. You need to use:

string StringUtil::Reverse(string phrase)
{
   ...
}

Upvotes: 0

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