/// <summary>
/// 随机打乱字符串中的所有字符
/// </summary>
/// <param name="str">需要被打乱的字符串</param>
/// <param name="seed">种子</param>
/// <returns>被打乱的字符串</returns>
public static string Shuffle(string str, int?seed = null)
{
KGuard.Requires <ArgumentNullException>(str != null);
var random = KUtil.MakeRandom(seed);
var requested = new string[str.Length];
for (var i = 0; i < str.Length; i++)
{
var index = random.Next(0, str.Length - 1);
requested[i] = requested[i] ?? str.Substring(i, 1);
requested[index] = requested[index] ?? str.Substring(index, 1);
if (index == i)
{
continue;
}
var temp = requested[i];
requested[i] = requested[index];
requested[index] = temp;
}
return(KArray.Reduce(requested, (v1, v2) => v1 + v2, string.Empty));
}
/// <summary>
/// 在数组中根据条件取出一段值，并返回。
/// </summary>
/// <typeparam name="T">数组类型</typeparam>
/// <param name="source">规定数组</param>
/// <param name="start">
/// 取出元素的开始位置。
/// <para>如果该值设置为正数，则从前往后开始取</para>
/// <para>如果该值设置为负数，则从后向前取 <paramref name="start"/> 绝对值。-2 意味着从数组的倒数第二个元素开始</para>
/// </param>
/// <param name="length">
/// 被返回数组的长度
/// <para>如果该值设置为整数，则返回该数量的元素。</para>
/// <para>如果该值设置为负数，则则从后向前取 <paramref name="length"/> 绝对值位置终止取出。-1 意味着从数组的倒数第一个元素前终止</para>
/// <para>如果该值未设置，则返回从 <paramref name="start"/> 参数设置的位置开始直到数组末端的所有元素。</para>
/// </param>
/// <returns>取出的数组</returns>
public static T[] Slice <T>(T[] source, int start, int?length = null)
{
KGuard.Requires <ArgumentNullException>(source != null);
KUtil.NormalizationPosition(source.Length, ref start, ref length);
var requested = new T[length.Value];
Array.Copy(source, start, requested, 0, length.Value);
return(requested);
}
/// <summary>
/// 从数组中移除指定长度的元素，如果给定了<paramref name="replSource"/>参数，那么新元素从<paramref name="start"/>位置开始插入
/// </summary>
/// <typeparam name="T">数组类型</typeparam>
/// <param name="source">规定数组</param>
/// <param name="start">
/// 删除元素的开始位置。
/// <para>如果该值设置为正数，则从前往后开始删除</para>
/// <para>如果该值设置为负数，则从后向前取 <paramref name="start"/> 绝对值。-2 意味着从数组的倒数第二个元素开始</para></param>
/// <param name="length">
/// 删除元素的个数，也是被返回数组的长度
/// <para>如果该值设置为整数，则返回该数量的元素。</para>
/// <para>如果该值设置为负数，则则从后向前取 <paramref name="length"/> 绝对值位置终止删除。-1 意味着从数组的倒数第一个元素前删除</para>
/// <para>如果该值未设置，则返回从 <paramref name="start"/> 参数设置的位置开始直到数组末端的所有元素。</para>
/// </param>
/// <param name="replSource">在start位置插入的数组</param>
/// <returns>被删除的数组</returns>
public static T[] Splice <T>(ref T[] source, int start, int?length = null, T[] replSource = null)
{
KGuard.Requires <ArgumentNullException>(source != null);
KUtil.NormalizationPosition(source.Length, ref start, ref length);
var requested = new T[length.Value];
if (length.Value == source.Length)
{
// 现在移除所有旧的元素，然后用新的元素替换。
Array.Copy(source, requested, source.Length);
source = replSource ?? new T[] { };
return(requested);
}
Array.Copy(source, start, requested, 0, length.Value);
if (replSource == null || replSource.Length == 0)
{
var newSource = new T[source.Length - length.Value];
// 现在只删除不插入
if (start > 0)
{
Array.Copy(source, 0, newSource, 0, start);
}
Array.Copy(source, start + length.Value, newSource, start, source.Length - (start + length.Value));
source = newSource;
}
else
{
var newSource = new T[source.Length - length.Value + replSource.Length];
// 删除并且插入
if (start > 0)
{
Array.Copy(source, 0, newSource, 0, start);
}
Array.Copy(replSource, 0, newSource, start, replSource.Length);
Array.Copy(source, start + length.Value, newSource, start + replSource.Length,
source.Length - (start + length.Value));
source = newSource;
}
return(requested);
}
/// <summary>
/// 生成一个随机字母（含大小写），数字的字符串。
/// </summary>
/// <param name="length">字符串长度</param>
/// <param name="seed">种子</param>
/// <returns>随机的字符串</returns>
public static string Random(int length = 16, int?seed = null)
{
KGuard.Requires <ArgumentOutOfRangeException>(length > 0);
var requested = string.Empty;
var random = KUtil.MakeRandom(seed);
for (int len; (len = requested.Length) < length;)
{
var size = length - len;
var bytes = new byte[size];
random.NextBytes(bytes);
var code = Replace(new[] { "/", "+", "=" }, string.Empty, Convert.ToBase64String(bytes));
requested += code.Substring(0, Math.Min(size, code.Length));
}
return(requested);
}
/// <summary>
/// 计算子串在字符串中出现的次数
/// <para>该函数不计数重叠的子串</para>
/// </summary>
/// <param name="str">规定字符串</param>
/// <param name="subStr">子字符串</param>
/// <param name="start">起始位置</param>
/// <param name="length">需要扫描的长度</param>
/// <param name="comparison">扫描规则</param>
/// <returns>子字符串出现的次数</returns>
public static int SubstringCount(string str, string subStr, int start = 0, int?length = null, StringComparison comparison = StringComparison.CurrentCultureIgnoreCase)
{
KGuard.Requires <ArgumentNullException>(str != null);
KGuard.Requires <ArgumentNullException>(subStr != null);
KUtil.NormalizationPosition(str.Length, ref start, ref length);
var count = 0;
while (length.Value > 0)
{
int index;
if ((index = str.IndexOf(subStr, start, length.Value, comparison)) < 0)
{
break;
}
count++;
length -= index + subStr.Length - start;
start = index + subStr.Length;
}
return(count);
}
/// <summary>
/// 将规定数组中的元素打乱
/// </summary>
/// <typeparam name="T">数组类型</typeparam>
/// <param name="source">规定数组</param>
/// <param name="seed">种子</param>
/// <returns>打乱后的数组</returns>
public static T[] Shuffle <T>(T[] source, int?seed = null)
{
KGuard.Requires <ArgumentNullException>(source != null);
var requested = new T[source.Length];
Array.Copy(source, requested, source.Length);
var random = KUtil.MakeRandom(seed);
for (var i = 0; i < requested.Length; i++)
{
var index = random.Next(0, requested.Length - 1);
if (index == i)
{
continue;
}
var temp = requested[i];
requested[i] = requested[index];
requested[index] = temp;
}
return(requested);
}