Re: function doesn't return simply skip the return line
On Jul 21, 4:50 pm, hirsh....@gmail.com wrote:
Hello to all, i have the following functions:
string File::readLine(){
char ch;
string str;
ch = read();
while(ch != LF && ch != CR && ch != -1){
Nothing to do with your problem, but there's no guarantee that a
char can ever take on the value of -1, so you've definitely got
something wrong here. I don't know a read() function which
takes no arguments, so I can't be sure, but the usual idiom
(from C) for this sort of thing is for functions which read a
single character to return an int, with a value in the range
0...UCHAR_MAX, or a negative value for EOF. But this supposes
that the returned value is stored in an int, and not a char.
str.append(1,ch);
Rather than "str += ch"? Strange.
ch = read();
}
if(ch == -1){
cout << "this line could not be read" << endl;
exit(1);
}
//take care of situation where the loop exited with LF but
//on a system that has CR.
int tmp = file->tellg();
Do you know what type ifstream::tellg returns? It isn't int.
if(read() != CR){ //if no CR available on system, return the ge=
t
pointer to it's correct location.
file->seekg(tmp);
}
What's the relationship between file and where ever read()
accesses. If read() is accessing file, and file is an istream,
why not use file directly, e.g.:
if ( file->peek() == CR ) {
file->get() ;
}
return str;
}
the function is executed correctly but in the end it skips the "return
str" line,
and tun flies with an error.
What does that mean? "Tun flies with an error." I don't
understand it. If you reach the return statement, it will be
executed. It may cause an exception to be thrown (because str
must be copied, and copying a string may throw), but unless
you're right at the limit in memory use, it's highly unlikely.
Another possibility (very likely, IMHO) is that you've corrupted
the free space arena sometime earlier, and you just happened to
hit the problem when copying str.
debugging took me to a qt class moc_myclass.cpp (it's a qt
project in eclipse)
to a line where it says "_id -= 1;"
inside a function called "int myclass::qt_metacall(...)"
I doubt that that's significant, but you never know. More
likely something else is corrupt, which results in your stack
being corrupted, which results in your returning someplace else
than where you came from.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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