Dynamically Create A Printf String Format
Formatting a string with
Printf requires defining a format for that
let str = Printf.sprintf("%6s", "dope"); /* str => " dope" */
The format is the first argument. At compile-time it is interpreted as a
format6 type value.
So, what if you want a dynamically created format value? Simply
concatenating some strings together won't do it because then the type will
string and that's not going to compile.
function can help.
let some_num = 6; let format_str = "%" ++ string_of_int(some_num) ++ "s"; let format = Scanf.format_from_string(format_str, "%s"); let str = Printf.sprintf(format, "dope"); /* str => " dope" */
We can convert our string that has the appearance of a format into an actual
format6 type. To do this, we have to tell
format_from_string what types
each of the formats is going to have -- hence the second argument