Question

I am trying to write a template class for Insertion Sort algorithm. But I am encountering the error “error C4430: missing type specifier – int assumed. Note: C++ does not support default-int”. But I am not sure why this error is coming.

insertion_sort.h file as follows:

     #pragma once
     #include <iostream>
     template <typename T,int SIZE>
     class insertion_sort
     {
           T data[SIZE];
      public:
       insertion_sort(void);
       void set_data();
       void sort_data();
       void show_data();
      ~insertion_sort(void);
     };

insertion_sort.cpp file as follows:

#include <iostream>
#include "insertion_sort.h"
using namespace std;


template <typename T,int SIZE>
insertion_sort<T,SIZE>::insertion_sort(void)
{
    typedef typename int i;
for(i=0;i<SIZE;i++)
   data[i]=NULL;
}
template <typename T,int SIZE>
insertion_sort<T,SIZE>::set_data(void)
{
    typedef typename int i;
    cout<<"ENTER THE DATA"<<endl;
    for(i=0;i<SIZE;i++)
       cin>>data[i];
}
template <typename T,int SIZE>
insertion_sort<T,SIZE>::sort_data()
{
    typedef typename int i,j;
    T key;
    for(i=1;i<SIZE;i++)
    {
          j=i-1;
          key=data[j]
          while(data[j-i]>key)
          {
             data[j]=data[j-1];
             j--;
           };
           data[j+1]=key;
     }
}
 template <typename T,int SIZE>
insertion_sort<T,SIZE>::show_data()
{
typedef typename int i;
for(i=0;i<SIZE;i++)
    cout<<data[i]<<"\t";
}
template <typename T,int SIZE>
insertion_sort<T,SIZE>::~insertion_sort(void)
{
}

main.cpp file is as follows:

#include <iostream>
#include "insertion_sort.h"

using namespace std;

int main()
{
    insertion_sort<char,5> S;
    S.set_data();
    S.sort_data();
    S.show_data();
    return 0;
}

When I build the code I am getting following error:

c:\documents and settings\devil_den\my documents\visual studio 2008\projects\sorting_algorithms\sorting_algorithms\insertion_sort.cpp(17) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

c:\documents and settings\devil_den\my documents\visual studio 2008\projects\sorting_algorithms\sorting_algorithms\insertion_sort.cpp(34) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

c:\documents and settings\devil_den\my documents\visual studio 2008\projects\sorting_algorithms\sorting_algorithms\insertion_sort.cpp(41) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

main.cpp
Generating Code...
Build log was saved at "file://c:\Documents and Settings\devil_den\My Documents\Visual Studio 2008\Projects\Sorting_Algorithms\Sorting_Algorithms\Debug\BuildLog.htm"
Sorting_Algorithms - 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

The definitions of set_data(), sort_data() and show_data() are missing their return types. All are declared to have return type of void so just add to the definitions:

template <typename T,int SIZE>
void insertion_sort<T,SIZE>::set_data(void)
{
    // snip ...
}