Something like this?
public int ReverseInt(int num)
{
int result=0;
while (num>0)
{
result = result*10 + num%10;
num /= 10;
}
return result;
}
As a hackish one-liner (update: used Benjamin's comment to shorten it):
num.ToString().Reverse().Aggregate(0, (b, x) => 10 * b + x - '0');
A speedier one-and-a-quarter-liner:
public static int ReverseOneLiner(int num)
{
for (int result=0;; result = result * 10 + num % 10, num /= 10) if(num==0) return result;
return 42;
}
It's not a one-liner because I had to include return 42;
. The C# compiler wouldn't let me compile because it thought that no code path returned a value.
P.S. If you write code like this and a co-worker catches it, you deserve everything he/she does to you. Be warned!
EDIT: I wondered about how much slower the LINQ one-liner is, so I used the following benchmark code:
public static void Bench(Func<int,int> myFunc, int repeat)
{
var R = new System.Random();
var sw = System.Diagnostics.Stopwatch.StartNew();
for (int i = 0; i < repeat; i++)
{
var ignore = myFunc(R.Next());
}
sw.Stop();
Console.WriteLine("Operation took {0}ms", sw.ElapsedMilliseconds);
}
Result (10^6 random numbers in positive int32 range):
While loop version:
Operation took 279ms
Linq aggregate:
Operation took 984ms
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