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Mac Forum / Programming / CodeWarrior / May 2005BSD tellg() not working?
I have a project which uses MSL_C++_BSD_C_Mach-O.lib and I've noticed that tellg() returns -1 when I think it should be returning 0. I've tried the same code using the MSL C and it does return 0. Here is a snippet of what I'm doing. I have my bsd paths before MSL. Anyone have any ideas? Thanks -doug #include <fstream> #include <iostream> #include <string.h> int main(int argc, char * const argv[]) { std::ifstream stream(argv[1]); unsigned long pos; char line[256]; pos = stream.tellg(); stream.read(line, 50); std::cout << "tellg: " << pos << std::endl; std::cout << "[" << line << "]" << std::endl; return 0; } > I have a project which uses MSL_C++_BSD_C_Mach-O.lib and I've noticed > that tellg() returns -1 when I think it should be returning 0. I've [quoted text clipped - 20 lines] > return 0; > } Are you sure that the file is getting opened in the first place? Default working directories can unfortunately differ between C libs. If stream isn't open, then tellg() would return -1. -Howard Yes, the file does open. That's why I read a little of the file and echo to the screen. > Yes, the file does open. That's why I read a little of the file and > echo to the screen. Sorry, I'm having trouble duplicating your symptoms. If the file successfully opens, I keep getting a return of 0 from tellg() in your example. The only suggestion I'm coming up with at the moment is to initialize your "line" to zero to ensure that you're not printing out garbage: char line[256] = {0}; Assuming a successful open, the only calls to BSD C your program should be making (under tellg) is: fseek(file_, 0, SEEK_CUR); ftell(file_); (these calls are made in <msl_C_filebuf> in the function seek_device) If either of those calls fail, then tellg() will return -1 as you report. But I currently do not see a reason for these calls to fail, assuming of course that file_ points to a valid, open, FILE. -Howard Nope. I placed a memset in there to zero out line and the file reads ok but -1 is still being returned. Maybe I have something messed with my project. Can I email you my project? > Nope. I placed a memset in there to zero out line and the file reads > ok but -1 is still being returned. Maybe I have something messed > with my project. Can I email you my project? Sure. -Howard |
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