On 02/06/2009 01:23 PM, bruce.lab...@autoliv.com wrote:
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...)C++ strings (from the STL) are strictly C++ template classes. The std::string function, c_str() is what you want. You are not using it as a function.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 = jjfilenamec = filename.c_str; // <===== COMPILER DIES HERE ==========fidjj = fopen(filenamec, "rb"); // <===== location of second errorif (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 snippetCompiler 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!)
filenamec = filename.c_str; // <===== COMPILER DIES HERE strcpy(filenamec,filename.c_str()); // This is the correct construct in your code.
Or: char *filenamec = filename.c_str()); You may need to use const char *. -- Jerry Feldman <g...@blu.org> Boston Linux and Unix PGP key id: 537C5846 PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB CA3B 4607 4319 537C 5846
signature.asc
Description: OpenPGP digital signature
_______________________________________________ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
