How to insert a string in side other string

[mpage]

Hi, this is my first post and i dont have a very good english so I'll try to do my best....

I'm working with image processing in C++, for that I read the file name from console , I open the file I work with it and then I want to create a file with the same name of the image with a "_res" added....

so for example if the image name is "image1.bmp " what i want to save is "image1_res.bmp ".... but when I'm working with te string for same reason i can only get staff like this... "image1@*$_res. bmp".

For opening the image and saving it im using a open source libery. : FreeImage.

This is what im doing....:

     char *input_dir = new char[260];;
     char image_path[260];            
     getFilePath(input_dir, image_path);   
   
     // batch convert all supported bitmaps
     _finddata_t finddata;
     long handle = _findfirst(image_path, &finddata);
     //
      ....
     //

[mpage]

and when i want to create the new file name i do this

       int largoNom = strlen(finddata.name);
       largoNom += 5;
       char *unique = new char[largoNom];
       largoNom -= 9;
       strncpy(unique,finddata.name,largoNom);
       strcat(unique,"_res");
       strcat(unique,".bmp");
       FunFI::GenericWriter(dib, unique, PNG_DEFAULT);

If I show in console unique and finddata.name its the same thing i was telling you, so it isnt a problem with te libery.