持續(xù)更新的.NET實(shí)用擴(kuò)展方法,具體內(nèi)容如下
1. 字符串轉(zhuǎn)換為可空數(shù)值類型(int, long, float...類似)
/// <summary> /// 將字符串轉(zhuǎn)換成32位整數(shù),轉(zhuǎn)換失敗返回null /// </summary> /// <param name="str">轉(zhuǎn)換的字符串</param> /// <returns>轉(zhuǎn)換之后的整數(shù),或null</returns> public static int? TryParseToInt32(this string str) { if (string.IsNullOrWhiteSpace(str)) return null; var result = 0; if (int.TryParse(str, out result)) return result; else return null; }
2. 去除子字符串
/// <summary> /// 去除子字符串 /// </summary> /// <param name="str">原字符串</param> /// <param name="substring">要去除的字符串</param> /// <returns>去除子字符串之后的結(jié)果</returns> public static string DeSubstring(this string str, string substring) { if (string.IsNullOrEmpty(str) || string.IsNullOrEmpty(substring) || !str.Contains(substring)) { return str; } return Regex.Replace(str, Regex.Escape(substring), string.Empty); } /// <summary> /// 去除子字符串 /// </summary> /// <param name="str">原字符串</param> /// <param name="substrings">要去除的子字符串</param> /// <returns>去除子字符串之后的結(jié)果</returns> public static string DeSubstring(this string str, params string[] substrings) { if (string.IsNullOrEmpty(str)) return str; if (substrings == null) return str; var newStr = str; foreach (var item in substrings) { newStr = newStr.DeSubstring(item); } return newStr; }
3. 獲取子序列
/// <summary> /// 獲取子序列 /// </summary> /// <typeparam name="T">序列中元素類型</typeparam> /// <param name="source">源數(shù)據(jù)</param> /// <param name="startIndex">開始索引(返回時(shí)包括)</param> /// <param name="endIndex">結(jié)束索引(返回時(shí)包括)</param> /// <returns>子序列</returns> public static IEnumerable<T> SubEnumerable<T>(this IEnumerable<T> source, int startIndex, int endIndex) { if (source == null) yield return default(T); var length = source.Count(); if (startIndex < 0 || endIndex < startIndex || startIndex >= length || endIndex >= length) throw new ArgumentOutOfRangeException(); var index = -1; foreach (var item in source) { index++; if (index < startIndex) continue; if (index > endIndex) yield break; yield return item; } }
4. 通過指定鍵對(duì)序列去重, 不必實(shí)現(xiàn)IEqualityComparer接口
/// <summary> /// 通過對(duì)指定的值進(jìn)行比較返回序列中的非重復(fù)元素。 /// </summary> /// <typeparam name="T">序列中元素類型</typeparam> /// <typeparam name="TResult">指定的比較屬性類型</typeparam> /// <param name="source">源數(shù)據(jù)</param> /// <param name="selector">應(yīng)用于每個(gè)元素的轉(zhuǎn)換函數(shù)</param> /// <returns>一個(gè)包含源序列中的按指定屬性非重復(fù)元素</returns> public static IEnumerable<T> Distinct<T, TResult>(this IEnumerable<T> source, Func<T, TResult> selector) { if (source == null) throw new ArgumentNullException(nameof(source)); if (selector == null) throw new ArgumentNullException(nameof(selector)); var set = new HashSet<TResult>(); foreach (var item in source) { var result = selector(item); if (set.Add(result)) { yield return item; } } }
5. 獲取序列中重復(fù)的元素序列, 原理和去重類似
/// <summary> /// 通過對(duì)指定的值進(jìn)行比較返回序列中重復(fù)的元素 /// </summary> /// <typeparam name="T">序列中的數(shù)據(jù)類型</typeparam> /// <typeparam name="TResult">指定的比較屬性類型</typeparam> /// <param name="source">源數(shù)據(jù)</param> /// <param name="selector">應(yīng)用于每個(gè)元素的轉(zhuǎn)換函數(shù)</param> /// <returns>一個(gè)包含源序列中的按指定元素的重復(fù)元素</returns> public static IEnumerable<T> Identical<T>(this IEnumerable<T> source) { if (source == null) throw new ArgumentNullException(nameof(source)); var setT = new HashSet<T>(); foreach (var item in source) { if (!setT.Add(item)) { yield return item; } } } /// <summary> /// 通過對(duì)指定的值進(jìn)行比較返回序列中重復(fù)的元素 /// </summary> /// <typeparam name="T">序列中的數(shù)據(jù)類型</typeparam> /// <typeparam name="TResult">指定的比較屬性類型</typeparam> /// <param name="source">源數(shù)據(jù)</param> /// <param name="selector">應(yīng)用于每個(gè)元素的轉(zhuǎn)換函數(shù)</param> /// <returns>一個(gè)包含源序列中的按指定元素的重復(fù)元素</returns> public static IEnumerable<T> Identical<T, TResult>(this IEnumerable<T> source, Func<T, TResult> selector) { if (source == null) throw new ArgumentNullException(nameof(source)); if (selector == null) throw new ArgumentNullException(nameof(selector)); var setTResult = new HashSet<TResult>(); foreach (var item in source) { var result = selector(item); if (!setTResult.Add(result)) { yield return item; } } }
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