每2个字符拆分字符串 [英] Split string by every 2 characters

问题描述

您好，

我只想在项目工作中完成一项小任务。

我想用每两个字符用'：'拆分字符串。我在下面给出了详细的示例： -

如果输入字符串是 12345678 ，我看输出是 12：34：56：78





谢谢



Vasanth

Hello,
I just wanted one small task in my project work.
I want to split string with ':' by every two characters. I have shows detailed example below :-
If Input string is "12345678", i looking the output is "12:34:56:78"


Thanks

Vasanth

推荐答案

好的，既然我们要沿着LINQ路线走下去（参见解决方案＃7），这里有一个更有效的方法：:)

OK, since we're going down the LINQ route (see solution #7), here's a slightly more efficient method: :)

public static class ExtensionMethods
{
    public static IEnumerable<T> DelimitWith<T>(this IEnumerable<T> source, T separator, int itemsPerGroup = 1)
    {
        if (source == null) throw new ArgumentNullException("source");
        if (itemsPerGroup < 1) throw new ArgumentOutOfRangeException("itemsPerGroup");
        return DelimitWithIterator(source, separator, itemsPerGroup);
    }

    private static IEnumerable<T> DelimitWithIterator<T>(IEnumerable<T> source, T separator, int itemsPerGroup)
    {
        int count = 0;
        foreach (T item in source)
        {
            if (count == itemsPerGroup)
            {
                yield return separator;
                count = 0;
            }
            checked
            {
                count++;
            }

            yield return item;
        }
    }
}

string source = "1234567890";
char[] resultChars = source.DelimitWith(':', 2).ToArray();
string result = new string(resultChars);

可能有更简单，更优雅的方法，但是...

There are probably simpler and more elegant ways to do this, but...

string s = "12345678";
StringBuilder sb = new StringBuilder();
int index = 0;
foreach (char c in s)
    {
    sb.AppendFormat("{0}{1}", c, (index++ & 1) == 0 ? "" : ":");
    }
s = sb.ToString().Trim(':');

会这样做。

Will do it.

为了好玩它：OriginalGriff提供的代码示例稍有不同（请投票）对于OriginalGriff的答案，而不是这一个）：

For the fun of it: a slight variation on the code example provided by OriginalGriff (please vote for OriginalGriff's answer, not this one):

string str = "123456789";

//check string is even in length
if (str.Length % 2 == 1) throw new ArgumentOutOfRangeException ("String length must be even");

StringBuilder sb = new StringBuilder();

int index = 0;

foreach (char c in str)
{
    sb.Append(c);
    if ((++index % 2)  == 0) sb.Append(":");
}

str = sb.Remove(sb.Length - 1, 1).ToString();

如果你真的想要花哨，并尝试将循环迭代次数减少一半：

If you really want to get fancy, and try to reduce the number of loop iterations by half:

for (int i = 1, j = 0; i < (str.Length / 2); i += 2, j+= 2)
{
    sb.Append(str[j]);
    sb.Append(str[i]);
    sb.Append(':');
}

str = sb.Remove(sb.Length - 1, 1).ToString();

这里使用的额外StringBuilder.Appends的成本是否超过执行循环次数的优势，并且消除了一个布尔测试：我的猜测是，在数百万次执行的情况下，它会略微加快。

Whether the "cost" of the extra StringBuilder.Appends used here "outweighs" the advantage of executing the loop half the number of times, and eliminating one boolean test: my guess is that it would be marginally faster in the context of millions of executions.

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