On Tuesday, 22 December 2015 at 17:23:11 UTC, Andrew Chapman
wrote:
On Tuesday, 22 December 2015 at 17:18:16 UTC, cym13 wrote:
On Tuesday, 22 December 2015 at 17:15:27 UTC, Andrew Chapman
wrote:
Sorry if this is a silly question but is the to! method from
the conv library the most efficient way of converting an
integer value to a string?
e.g.
string s = to!string(100);
I'm seeing a pretty dramatic slow down in my code when I use
a conversion like this (when looped over 10 million
iterations for benchmarking).
Cheers!
Out of curiosity a slow down compared to what? No conversion
at all?
Yeah, if I include a simple conversion in my loop:
for({int i; i = 0;} i < num; i++) {
//string s = to!string(i);
Customer c = Customer(i, "Customer",
"99998888", i * 2);
string result = objS.serialize(c);
}
If I uncomment the "string s" line I'm seeing a 20% increase in
running time, which given what's going on the rest of the code
is quite surprising. I've tried compiling with both dmd and
ldc2 - it's the same under both.
Cheers.
Dynamic memory allocation is expensive. If the string is
short-lived, allocate it on the stack:
enum maxDigits = to!string(ulong.max).length;
foreach(i; 0 .. num) {
char[maxDigits] buffer = void;
auto c = Customer(sformat(buffer[], "%s", i));
string result = objS.serialize(c);
}
Note that this is unsafe if the string (sformat's return value)
outlives the loop iteration, as this is `buffer`'s scope.
