Efficient way to do this

[Steven Blair]

Hi,

I get passed a string like these examples:

3.1
4.23
1.1
5

I need to seperate the values into two integer variables.
So 3.1 would become

int var1, var2;

//var1 should have 3
//var2 should have 1

if it was 4.23

//var1 should have 4
//var2 should have 23

This is will be on a part of the system, where performance is critical
and need an efficient method for processing strings like this.

Thanks for the help in advance.

Steven
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[Marc Gravell]

How about something like:
private static int[] Parse(string value) {
string[] elements = value.Split('.');
int length = elements.Length;
int[] values = new int[length];
for (int i = 0; i < length; i++) {
values[i] = int.Parse(elements[i]);
}
return values;
}

If you know there are never more than 2 parts, then you might be able to
tweak bits of it, but doubt it would be worth it...

Marc

[Laura T]

Efficient depends on various parameters like speed, memory usage ecc.
I'd use something like this:

string sval = "44.55";
int v1, v2;

int s = sval.IndexOf('.'); // linear but small strings
if (s < 0) // Case no decimals
{
v1 = Convert.ToInt32(sval); // full integer
}
else
{
v1 = Convert.ToInt32(sval.Substring(0, s)); // temp string
(fast no gc)
v2 = Convert.ToInt32(sval.Substring(s + 1)); // idem
}
"Steven Blair" <st**********@btinternet.comha scritto nel messaggio
news:eh**************@TK2MSFTNGP04.phx.gbl...

Hi,

I get passed a string like these examples:

3.1
4.23
1.1
5

I need to seperate the values into two integer variables.
So 3.1 would become

int var1, var2;

//var1 should have 3
//var2 should have 1

if it was 4.23

//var1 should have 4
//var2 should have 23

This is will be on a part of the system, where performance is critical
and need an efficient method for processing strings like this.

Thanks for the help in advance.

Steven
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[Christof Nordiek]

Hi Laura

why do you say 'no gc' in the line with Substring method. The Substring
method surely creates a new string-instance on the GC-Heap.
To avoid this string instances, one has also to avoid the Convert class and
the Parse method at all. It could be possible, to access the single chars
from the string and calculate the values directly.
But i'm not sure if this really matters. To know this one has to make
performance tests.

"Laura T" <la******@yahoo.comschrieb im Newsbeitrag
news:ek**************@TK2MSFTNGP02.phx.gbl...

Efficient depends on various parameters like speed, memory usage ecc.
I'd use something like this:

string sval = "44.55";
int v1, v2;

int s = sval.IndexOf('.'); // linear but small strings
if (s < 0) // Case no decimals
{
v1 = Convert.ToInt32(sval); // full integer
}
else
{
v1 = Convert.ToInt32(sval.Substring(0, s)); // temp
string (fast no gc)
v2 = Convert.ToInt32(sval.Substring(s + 1)); // idem
}
"Steven Blair" <st**********@btinternet.comha scritto nel messaggio
news:eh**************@TK2MSFTNGP04.phx.gbl...

>Hi,

I get passed a string like these examples:

3.1
4.23
1.1
5

I need to seperate the values into two integer variables.
So 3.1 would become

int var1, var2;

//var1 should have 3
//var2 should have 1

if it was 4.23

//var1 should have 4
//var2 should have 23

This is will be on a part of the system, where performance is critical
and need an efficient method for processing strings like this.

Thanks for the help in advance.

Steven
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[Adityanand Pasumarthi]

Hi Steven,

Here is my solution...

long st = DateTime.Now.Ticks;
for(int i = 1; i <= 1000000; i++)
{
string sval = "4.23";
int v1 = 0;
int v2 = 0;
int s = sval.IndexOf('.');
if (s < 0)
{
int len = sval.Length;
for(int j = 0; j < len; j++) v1 = (v1 * 10) + ((int) sval[j] - 48);
}
else
{
int len = sval.Length;
for(int j = 0; j < s; j++) v1 = (v1 * 10) + ((int) sval[j] - 48);
for(int j = s + 1; j < len; j++) v2 = (v2 * 10) + ((int) sval[j] - 48);
}
//Console.WriteLine(v1);
//Console.WriteLine(v2);
}
long et = DateTime.Now.Ticks;
Console.WriteLine("Time: {0}",(et - st)/10000);

My approach has 0 Gen 0 collections, no heap memory and 10 times (1000%)
faster than other 2 solutions. Here are the stats taken from Windows Profiler
my 1.7 GHz single processor WIn 2K machine with 1 GB RAM.

Parse static method
-------------------------
445678.989 - 1 million iterations took 2300 milliseconds - 200 (Gen 0
collections) - 62 KB (Bytes in all Heaps)

445678 - 1 million iterations took 1200 milliseconds - 90 (Gen 0
collections) - 62 KB (Bytes in all Heaps)

4.4 - 1 million iterations took 1800 milliseconds - 200 (Gen 0 collections)
- 62 KB (Bytes in all Heaps)

SubString
------------
445678.989 - 1 million iterations took 1400 milliseconds - 80 (Gen 0
collections) - 32 KB (Bytes in all Heaps)

445678 - 1 million iterations took 600 milliseconds - 0 (Gen 0 collections)
- 32 KB (Bytes in all Heaps)

4.4 - 1 million iterations took 1200 milliseconds - 80 (Gen 0 collections) -
32 KB (Bytes in all Heaps)

My approach
----------------
445678.989 - 1 million iterations took 240 milliseconds - 0 (Gen 0
collections) - 0 KB (Bytes in all Heaps)

445678 - 1 million iterations took 175 milliseconds - 0 (Gen 0 collections)
- 0 KB (Bytes in all Heaps)

4.4 - 1 million iterations took 95 milliseconds - 0 (Gen 0 collections) - 0
KB (Bytes in all Heaps)

This is with .Net 1.1. I'll post you my results for .Net 2.0 soon.

Regards,
Aditya.P

"Steven Blair" wrote:

Hi,

I get passed a string like these examples:

3.1
4.23
1.1
5

I need to seperate the values into two integer variables.
So 3.1 would become

int var1, var2;

//var1 should have 3
//var2 should have 1

if it was 4.23

//var1 should have 4
//var2 should have 23

This is will be on a part of the system, where performance is critical
and need an efficient method for processing strings like this.

Thanks for the help in advance.

Steven
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