expected constructor destructor or type conversion before token

Question

Compiling polygone h and polygone cc gives error   polygone cc 5 19  error  expected constructor  destructor  or type conversion before         token   Code     polygone h   if  defined   POLYGONE H      define   POLYGONE H      include  lt iostream gt   class Polygone        public          Polygone              Polygone std  string fichier          endif   and     polygone cc   include  lt iostream gt    include  lt fstream gt    include  polygone h   Polygone  Polygone string nom        std  ifstream fichier  nom  ios  in       std  string line       if  fichier is open                  while   fichier good                           getline  fichier  line               std  cout  lt  lt  line  lt  lt  std  endl                      else               std  cerr  lt  lt   Erreur a l ouverture du fichier   lt  lt  std  endl             ifstream fich1  argv 1   ios  in     My guess is that the compiler is not recognising Polygone  Polygone string nom  as a constructor  but  if this actually is the case  I have no idea why   Any help

User · Answer

This is not only a  newbie  scenario   I just ran across this compiler message  GCC 5 4  when refactoring a class to remove some constructor parameters   I forgot to update both the declaration and definition  and the compiler spit out this unintuitive error     The bottom line seems to be this  If the compiler can t match the definition s signature to the declaration s signature it thinks the definition is not a constructor and then doesn t know how to parse the code and displays this error   Which is also what happened for the OP   std  string is not the same type as string so the declaration s signature differed from the definition s and this message was spit out    As a side note  it would be nice if the compiler looked for almost-matching constructor signatures and upon finding one suggested that the parameters didn t match rather than giving this message

User · Answer

You are missing the std namespace reference in the cc file  You should also call nom c str    because there is no implicit conversion from std  string to const char   expected by ifstream s constructor   Polygone  Polygone std  string nom        std  ifstream fichier  nom c str    std  ifstream  in

User · Answer

The first constructor in the header should not end with a semicolon   include  lt string gt  is missing in the header  string is not qualified with std   in the  cpp file  Those are all simple syntax errors  More importantly  you are not using references  when you should  Also the way you use the ifstream is broken  I suggest learning C   before trying to use it    Let s fix this up     polygone h   if  defined   POLYGONE H      define   POLYGONE H     include  lt iostream gt   include  lt string gt       class Polygone   public       declarations have to end with a semicolon  definitions do not   Polygone        why would we needs this    Polygone const std  string amp  fichier         endif   and    polygone cc    no need to include things twice  include  polygone h   include  lt fstream gt    Polygone  Polygone const std  string amp  nom      std  ifstream fichier  nom  ios  in       if  fichier is open               keep the scope as tiny as possible     std  string line         getline returns the stream and streams convert to booleans     while   std  getline fichier  line                std  cout  lt  lt  line  lt  lt  std  endl              else         std  cerr  lt  lt   Erreur a l ouverture du fichier   lt  lt  std  endl

[c++] expected constructor, destructor, or type conversion before ‘(’ token

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