convert string[] to int[]
Which is the fastest method for convert an stri开发者_开发知识库ng's array ["1","2","3"] in a int's array [1,2,3] in c#?
thanks
string[] arr1 = {"1","2","3"};
int[] arr2 = Array.ConvertAll(arr1, s => int.Parse(s));
The use of Array.ConvertAll
ensures (unlike LINQ Select
/ToArray
) that the array is initialized at the right size. You can possible get a shade quicker by unrolling, but not much:
int[] arr2 = new int[arr1.Length];
for(int i = 0 ; i < arr1.Length ; i++) {
arr2[i] = int.Parse(arr[i]);
}
If you need something faster still (perhaps bulk file/data handling), then writing your own parse might help; the inbuilt one handles a lot of edge-cases - if your data is simpler you really can cut this down a bit.
For an example of an alternative parser:
public static unsafe int ParseBasicInt32(string s)
{
int len = s == null ? 0 : s.Length;
switch(s.Length)
{
case 0:
throw new ArgumentException("s");
case 1:
{
char c0 = s[0];
if (c0 < '0' || c0 > '9') throw new ArgumentException("s");
return c0 - '0';
}
case 2:
{
char c0 = s[0], c1 = s[1];
if (c0 < '0' || c0 > '9' || c1 < '0' || c1 > '9') throw new ArgumentException("s");
return ((c0 - '0') * 10) + (c1 - '0');
}
default:
fixed(char* chars = s)
{
int value = 0;
for(int i = 0; i < len ; i++)
{
char c = chars[i];
if (c < '0' || c > '9') throw new ArgumentException("s");
value = (value * 10) + (c - '0');
}
return value;
}
}
}
var values = new string[] { "1", "2", "3" };
values.Select(x => Int32.Parse(x)).ToArray();
I'd probably do:
string[] array = new[] { "1", "2" }; // etc.
int[] ints = array.Select(x => int.Parse(x)).ToArray();
if I could guarantee that the data would be only integers.
if not:
string[] array = new[] { "1", "2" }; // etc.
List<int> temp = new List<int>();
foreach (string item in array)
{
int parsed;
if (!int.TryParse(item, out parsed))
{
continue;
}
temp.Add(parsed);
}
int[] ints = temp.ToArray();
I suggest to iterate and int.TryParse()
Which one is faster in processing and conversion int.Parse(), int.TryParse(), Convert.Int32()
See Microsoft comparison of Parse , TryParse and ConvertTo
iterate and convert.
The is no fast way I know but you can use a "short way":
var numbers = new[] {"1", "2", "3"};
var result = numbers.Select(s => int.Parse(s));
int[] resultAsArray = result.ToArray();
And if you use PLink you get to compute the values in parallel.
string[] arr = new string[]{ "1", "2", "3" };
int[] lss = (from xx in arr
select Convert.ToInt32(xx)).ToArray();
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