Re: inconsistencies when compiling
* rory:
I'm having some inconsistencies in my program that I can't seem to
debug. Below is code that makes a copy of a binary file, appends a
unique ID and string to the copy of the binary file and then checks
the string by searching for the ID which is also a string and
retrieves the text that follows. I'm building the code with scons
along with some other applications that are part of the project. Here
is the strange thing. If I set a new unique string and compile on it's
own my code below works fine. If I then call scons to built all the
project files including the code below it doesn't work. If I then try
to build it on its own again it still doesn't work. The only way to
get it to work again is to change the string ID and compile it again
on its own. I know this is a strictly c++ language list and my post
does refer to scons but all scons does is call the g++ compiler. Can
anyone help me with this problem? Here is my code, although I don't
think the problem is with the code.
I can't help you with the main problem.
However, a few comments on the code.
////////////////////////////////////////////////////////////////////////////////////////////////////
int main(int argc, char *argv[])
{
if(argc<2){
Indentation is a good idea.
cout << "\nUsage: copy_append_read <csound file> <output filename>
\nExample: cabbage test.txt test.exe\n";
return 0;
}
std::string Text, str;
long begin, end;
Variables not used.
//make a copy of binary cabbage.dat with new name
int ret = copyfileC("cabbage.dat", argv[2]);
Make that a bool, and make it const.
if(!ret) cerr << "Error: Could not copy/create file, please make
sure that cabbage.dat is located in the same folder as cabbage";
Are you sure you really want to continue after issuing that message?
//read contents of input file
ifstream file(argv[1]);
while(!file.eof())
{
getline(file, str);
What if this call to getline fails?
Text = Text+str;
1. Unless you have a very smart compiler this construction will most
probably yield O(n^2) running time. Instead, do e.g.
Text += str;
2. Inconsistent naming convention.
3. Are you sure you want to strip out newlines from the file contents?
}
//write identifier and input file string to runtime
WriteData(argv[2], Text);
//test that data was written and can be retreived
ReadData(argv[2]);
}
///////////////////////////////////////////////////////////////////////////////////////////
//////// Make a copy of the runtime binary
///////////////////////////////////////////////////////////////////////////////////////////
int copyfileC(std::string oldFile, std::string newFile)
Should have result type bool.
Arguments should by default be "std::string const&".
{
int c;
FILE *in, *out;
in = fopen(oldFile.c_str(), "rb");
out = fopen(newFile.c_str(), "wb");
if(!in && !out)
return 0;
Confusing && and ||.
while((c=fgetc(in))!=EOF)
{
fputc(c,out);
if(ferror(out)) cout << "error when writing new file";
Are you sure you want to continue looping after issuing that message?
And shouldn't that message go to cerr?
}
fclose(in);
fclose(out);
return 1;
}
///////////////////////////////////////////////////////////////////////////////////////////
//////// Append magic marker and Text to the runtime binary
///////////////////////////////////////////////////////////////////////////////////////////
void WriteData(std::string binfile, std::string Text)
Arguments should by default be "std::string const&".
{
ofstream myFile (binfile.c_str(), ios::out | ios::binary |
ios::app);
if((myFile.rdstate() & ofstream::failbit | ofstream::badbit)!=0)
The above condition will always be true unless badbit is defined as 0.
Compiler should warn about it.
If it doesn't, up the warning level.
//write unique marker..
myFile.write ("porytest", 8);
This is the only statement governed by the above 'if'.
myFile.write (Text.c_str(),Text.length());
if(!myFile) cout << "Write Error..." ;
Shouldn't that be directed to cerr?
myFile.close();
}
///////////////////////////////////////////////////////////////////////////////////////////
//////// Test function to see if data was written correctly
///////////////////////////////////////////////////////////////////////////////////////////
void ReadData(std::string binfile)
Argument should by default be "std::string const&".
{
std::ifstream ifstr(binfile.c_str(),std::ios::binary);
std::stringstream temp;
Use std::ostringstream when you don't intend to read from it.
temp << ifstr.rdbuf();
const std::string sentinel("porytest");
const std::string::size_type data_pos(temp.str().find(sentinel,
0)+sentinel.length());
const std::string myText(temp.str().substr(data_pos));
cout << myText;
ifstr.close();
}
Rory.
Cheers, & hth.,
- Alf
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?