"Ian Collins" <ian-news@hotmail.coma écrit dans le message de news:
6dfkr9F22jb8U5@mid.individual.net...
Quote:
cplusplusquestion@gmail.com wrote:
Quote:
>I have a binary file like:
>>
>a bla bla bla bla
>b 12 23 34 80 38
>>
>a bla bla bla bla
>b 23 45 89 30 99
>>
>When I find first character of the line is 'a', I would like to skip
>reading this line, then go to next line. Any suggestion?
|
>
If it's a binary file, how do you know where the next line begins?
>
--
Ian Collins.
|
From what I see, you can do:
1. read a char until you get a number
2.read a char until you get a letter
do this steps util the end of file
here a way to do this (with little error checking), you can test it with a
bin file like this one
a bla bla bla blab 12 23 34 80 38a bla bla bla blab 23 45 89 30 99
it can be on a single line, it doesn't matter.
bool isNumeric(char tmp)
{
return tmp >= 48 && tmp <= 57; // from ascii table
}
bool isLetter(char tmp)
{
// from ascii table
return (tmp >= 65 && tmp <= 90) || // A-Z
(tmp >= 97 && tmp <= 122); // a-z
}
int main()
{
std::ifstream ifs("FileName.bin", ios_base::in | ios_base::binary);
string linea , lineb;
while(ifs)
{
// now read a line and b line
char tmp=0;
while(!isNumeric(tmp))
{
ifs.get(tmp);
if(ifs)
linea.push_back(tmp);
else
break;
}
int bpos = linea.rfind('b');
lineb.assign(linea,bpos,linea.size()-bpos);
linea.erase(linea.begin()+bpos, linea.end());
// now you do your stuff with linea
while(!isLetter(tmp))
{
ifs.get(tmp);
if(ifs)
lineb.push_back(tmp);
else
break;
}
// ok I assume the data in linea has been extracted and stored elsewhere
so I can clear the string
linea.clear();
size_t apos = lineb.rfind('a');
if(ifs)
{
linea.push_back('a');
lineb.erase(lineb.begin()+apos, lineb.end());
}
// now extract info from lineb ....
lineb.clear();
}
return 0;
}
--------------------
Eric Pruneau
File Reading
