由网友(雾尽眉目清)分享简介：什么是找到的正整数的位数的最佳方法？What is the best method to find the number of digits of a positive integer?我发现这3种基本方式：I have found this 3 basic methods:转换为字符串conversion to...

什么是找到的正整数的位数的最佳方法？

What is the best method to find the number of digits of a positive integer?

我发现这3种基本方式：

I have found this 3 basic methods:

转换为字符串

conversion to string

String s = new Integer(t).toString(); 
int len = s.length();

循环

for loop

for(long long int temp = number; temp >= 1;)
{
    temp/=10;
    decimalPlaces++;
} 

logaritmic计算

logaritmic calculation

digits = floor( log10( number ) ) + 1;

在这里，你可以计算出在大多数语言LOG10（X）= LN（X）/ LN（10）。

where you can calculate log10(x) = ln(x) / ln(10) in most languages.

首先，我认为该字符串的方法是最脏的一个，但我越去想它，我就越觉得这是最快的方法。或者是什么？

First I thought the string method is the dirtiest one but the more I think about it the more I think it's the fastest way. Or is it?

推荐答案

总是有这种方式：

n = 1;
if (i >= 100000000){i /= 100000000; n += 8;}
if (i >= 10000){i /= 10000; n += 4;}
if (i >= 100){i /= 100; n += 2;}
if (i >= 10){i /= 10; n += 1;}