On 10/14/2015 12:14 AM, Joel wrote:
Is there a fast way to get a number out of a text input?
Like getting '1.5' out of 'sdaz1.5;['.
Here's what I have at the moment:
string processValue(string s) {
string ns;
foreach(c; s) {
if (c >= '0' && c <= '9')
ns ~= c;
else if (c == '.')
ns ~= '.';
}
return ns;
}
Regular expressions:
import std.stdio;
import std.regex;
void main() {
auto input = "sdaz1.5;[";
auto pattern = ctRegex!(`([^-0-9.]*)([-0-9.]+)(.*)`);
auto m = input.matchFirst(pattern);
if (m) {
assert(m[0] == "sdaz1.5;["); // whole
assert(m[1] == "sdaz"); // before
assert(m[2] == "1.5"); // number
assert(m[3] == ";["); // after
}
}
1) I am not good with regular expressions. So, the floating point
selector [-0-9.]+ is very primitive. I recommend that you search for a
better one. :)
2) ctRegex is slow to compile. Replace ctRegex!(expr) with regex(expr)
for faster compilations and slower execution (probably unnoticeably slow
in most cases).
3) If you want to extract a number out of a constant string,
formattedRead (or readf) can be used as well:
import std.stdio;
import std.format;
void main() {
auto input = "Distance: 1.5 feet";
double number;
const quantity = formattedRead(input, "Distance: %f feet", &number);
assert(number == 1.5);
}
Ali
