| re: Stream input, critique my code?
"Donald Canton" <dcanton@rocketmail.com> wrote in message
news:c260a017.0405031157.4e706a82@posting.google.c om...[color=blue]
> Hi,
>
> My goal is to read a text file consisting of lines containing
> someone's name followed by one or more numeric values. All fields are
> tab-delimited. The name could be in any one of the following formats:
>
> John Doe
> J. Doe
> John H. Doe
>
> and will always be followed by at least one tab character. Here's the
> code:
>
> #include <fstream>
> #include <istream>
> #include <iostream>
> #include <string>
>
> int main()
> {
> std::ifstream inputfile("data.txt");
> if( !inputfile ) {
> std::cerr << "Can't open file: " << '\n';
> return -1;
> }
> std::istream& input = inputfile;[/color]
Why the above? Just use inputfile directly.
[color=blue]
> std::string name;
> double value;
>
> while ( std::getline(input, name, '\t') )
> {
> //do something with name, then read values
> while ( input >> value ) {
> //do something with value
> }
> input.clear(); //end of values, reset stream
> }
> return 0; //end of input
> }
>
> Are there any pitfalls in doing it this way? Suggestions?[/color]
It seems to work, but its tricky code that relies on the details on the
iostream library and the format of your input file. For instance it will be
defeated by a name that begins with a digit. You might think that will never
happen, but I know from experience you get all sorts of strange things in
large data sets (I remember the occasion when my code was defeated by
someone who had a superscripted digit in the middle of their name).
I would rather see code that reflects your requirements directly. I.e.
while (read a line)
{
split line at first tab into 'name' and 'values'
get name from 'name' (trim whitespace?)
create stringstream from 'values'
while (read a value)
{
do something with value
}
}
It might be more long winded but its a simple translation of your
requirements into code, with no trickery.
john
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