On Monday, 5 August 2013 at 15:18:42 UTC, John Colvin wrote:
On Monday, 5 August 2013 at 13:59:24 UTC, jicman wrote:
Greetings!
I have this code,
foreach (...)
{
if (std.string.tolower(fext[0]) == "doc" ||
std.string.tolower(fext[0]) == "docx" ||
std.string.tolower(fext[0]) == "xls" ||
std.string.tolower(fext[0]) == "xlsx" ||
std.string.tolower(fext[0]) == "ppt" ||
std.string.tolower(fext[0]) == "pptx")
continue;
}
foreach (...)
{
if (std.string.tolower(fext[0]) == "doc")
continue;
if (std.string.tolower(fext[0]) == "docx")
continue;
if (std.string.tolower(fext[0]) == "xls")
continue;
if (std.string.tolower(fext[0]) == "xlsx")
continue;
if (std.string.tolower(fext[0]) == "ppt")
continue;
if (std.string.tolower(fext[0]) == "pptx")
continue;
...
...
}
thanks.
josé
better:
foreach (...)
{
auto tmp = std.string.tolower(fext[0]);
if(tmp == "doc" || tmp == "docx"
|| tmp == "xls" || tmp == "xlsx"
|| tmp == "ppt" || tmp == "pptx")
{
continue;
}
}
but still not super-fast as (unless the compiler is very
clever) it still means multiple passes over tmp. Also, it
converts the whole string to lower case even when it's not
necessary.
If you have large numbers of possible matches you will probably
want to be clever with your data structures / algorithms. E.g.
You could create a tree-like structure to quickly eliminate
possibilities as you read successive letters. You read one
character, follow the appropriate branch, check if there are
any further branches, if not then no match and break. Else,
read the next character and follow the appropriate branch and
so on.... Infeasible for large (or even medium-sized)
character-sets without hashing, but might be pretty fast for
a-z and a large number of short strings.
As the Hispanic speaking community say, muchas gracias.
