C & C++ string confusion

[bruce.labitt at autoliv.com]

Maybe some on the list might know the answer to this...  I am trying to 
read n files, one at a time, and appending the data to a different file. 
Since the files are so large, I need to delete each of the n files, once I 
have captured the data. 

Why on earth am I doing this?  My arrays are too large to fit in memory 
all at once (I used up all 32GB!!) so I have to process each row of the 
matrix separately.  (It slows stuff way down...)

I find string manipulation in C to be a bit arcane.  This is what I have 
come up with so far.  Unfortunately, (maybe fortunately?) the compiler 
does not like my coding.  Oh yes, this has to be in a C or C++ dialect. 
(No "I can do this in x lines of your favorite language" comments. :) )

The code will be compiled using g++ on YDL to run on a QS22 (Cell 
Processor) = Linux content :)

/start code snippet

main()
{
 string filename;
 string shelldelcmd;
 string mydelstr;
 char filenum[4];
 char filenamec[20];
 FILE * fidjj;

 shelldelcmd.assign("rm -f ");

 for (jj=0; jj<1000; jj++)
 {
  filename.assign("out");
  sprintf(filenum, "%04d", jj); //generate string for file number, like 
"0010"
  filename.append(filenum);  // filename = "outxxxx", where xxxx = jj
  filenamec = filename.c_str;           // <=====  COMPILER DIES HERE 
==========

  fidjj = fopen(filenamec, "rb");       // <===== location of second error
  if (fidjj==NULL) {fputs ("File error, does not exist\n", stderr); 
exit(1);}

  fread some stuff...
  fclose(fidjj);

  mydelstr.assign(shelldelcmd);
  mydelstr.append(filename);
  mydelstr.append("\n");

  cout << "my delete string is : " << mydelstr << endl;
  system(mydelstr);     // delete the file I just read... !!!
  fwrite data to a different file...
 }
}

/end code snippet

Compiler error is: error; incompatible types of assignment of '<unresolved 
overloaded function type>' to 'char[20]'

If I just use the string "filename" instead of "filenamec" in fopen I get 
two errors, first the one in the previous paragraph, and second is: 

error: cannot convert 'std::string' to const char * for argument '1' to 
'FILE * fopen(const char *, const char*)'

If you think I should step away from the keyboard, well, unfortunately 
that is not an option.  I have to learn this stuff as I go along...  And 
no, I have never taken a class in C++.  I barely have the hang of C... 
FWIW, I tried it in C and suffered some string craziness like unexpected 
overwriting.  It was ugly...  This approach seems cleaner, except I do not 
know how to convert the C++ strings to be able to use ordinary C fopens...

Any tips or insight would be greatly appreciated...  (Awesome tips are 
rewarded with beer!) 


-Bruce

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