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ben-strasser / fast-cpp-csv-parser

fast-cpp-csv-parser
BSD 3-Clause "New" or "Revised" License
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Number and names of CSV columns only known at run-time #19

Closed jnhansen closed 8 years ago

jnhansen commented 8 years ago

Hi, firstly thanks for writing this CSV library!

I was wondering if it is possible to read a CSV file whose structure is only known at run-time. In particular, I have a vector of column headers (std::vector<std::string>) to read from the CSV which I would ideally like to pass to the parser directly – instead of a series of separate parameters which must be known at compile-time. The size of the vector is also only known at run-time.

I am sure I could use the LineReader class for this, however, if the changes required in the CSVReader class are only minor I might try and adapt it.

Do you think the class is apt for this purpose?

ben-strasser commented 8 years ago

Hi,

Unfortunately, I do not think that getting CSVReader to do that is easy.

read_row needs to have the types of its operants at compile time to decide what to convert the data to. This a very fundamental property of the interface design and I do not even know how a dynamic variant would look like.

jnhansen commented 8 years ago

Oh, I see. Didn't think about different types per column. In my particular case I would want all columns to be floating point and to be ignored if parsing into floating point fails. Or, alternatively, just take the char* output and do the parsing myself. I suppose I can get the LineReader to do the job for me.

rhl- commented 8 years ago

I agree, this appears to be a great tool besides this limitation. I am not sure in what universe the average user knows the number of columns they want to read from a csv in advance of compiling the code.