I have a string of numbers, like "31654918562314", and I want to convert it into an array of integers. The code I've written is:
string source = "31654918562314";
int[] numbers = new int[source.Length];
for (int i = 0; i < source.Length; i++)
{
numbers[i] = Convert.ToInt32(source.Substring(i, 1));
}
What improvements can I apply on this code? Is it the best ultimate code I can get to?
Note: I'm using C#. However, I also should implement this code in JavaScript.
I'm partial to using LINQ here. Jon has a point there on the conversion.
var str = "31654918562314";
var numbers = str.Select(c => c - '0').ToArray();
The most efficient code would be to use a plain loop and get the numerical value from the character code:
string source = "31654918562314";
int[] numbers = new int[source.Length];
for (int i = 0; i < source.Length; i++) {
numbers[i] = source[i] - '0';
}
In Javascript you would use the charCodeAt method to do the same:
var source = '31654918562314';
var numbers = new Array(source.length);
for (var i = 0; i < source.length; i++) {
numbers[i] = source.charCodeAt(i) - 48;
}
A performance test shows that using charCodeAt in a loop is 10-30 times faster than using a regular expression and parseInt: http://jsperf.com/string-to-array-of-numbers
var arr = [];
var matches = "54321".match(/\d/g);
for (var index = 0; index < matches.length; ++index) {
arr.push(parseInt(matches[index], 10));
}
Using map() method:
var arr = "54321".match(/\d/g).map(function(m){
return parseInt(m, 10);
});
0from each digit, rather than callConvert.ToInt32()orInt32.Parse(). \$\endgroup\$Char.GetNumericValuemsdn.microsoft.com/en-us/library/e7k33ktz.aspx \$\endgroup\$