增加string.TrimString扩展方法，可以去除头尾给定字符串

Falcon.SugarApi.Test/StringExtendTest.cs

@@ -112,5 +112,22 @@ namespace Falcon.SugarApi.Test
             Assert.IsTrue(result.Length == 1);
             Assert.IsTrue(result[0] == "abc");
         }
+
+        /// <summary>
+        /// 去除头尾字符
+        /// </summary>
+        [TestMethod]
+        public void TestTrimString() {
+            var str = @"abcabcffe222256256";
+            //去除头部的abc字符
+            var r = str.TrimString("abc");
+            Assert.AreEqual(r , "ffe222256256");
+            //去除尾部256字符
+            r = str.TrimString("","256");
+            Assert.AreEqual(r,"abcabcffe222");
+            //去除头部abc字符和尾部256字符
+            r = str.TrimString("abc","256");
+            Assert.AreEqual(r,"ffe222");
+        }
     }
 }

Falcon.SugarApi/StringExtend.cs

@@ -15,7 +15,7 @@ namespace Falcon.SugarApi
         /// </summary>
         /// <param name="str">字符串</param>
         /// <returns>空或null为True，否则False</returns>
-        public static bool IsNullOrEmpty(this string? str) => str==null||string.IsNullOrEmpty(str);
+        public static bool IsNullOrEmpty(this string? str) => str == null || string.IsNullOrEmpty(str);
         /// <summary>
         /// 字符串是否不为空或null
         /// </summary>
@@ -38,7 +38,7 @@ namespace Falcon.SugarApi
         /// <param name="splitChars"></param>
         /// <returns>字符串数组。当str为null时返回空数组</returns>
         public static string[] SplitStr(this string? str,params char[] splitChars)
-            => str.IsNullOrEmpty() ? Array.Empty<string>() : str.Split(splitChars.Length==0 ? new char[] { ',','，',';','；','.','。' } : splitChars,StringSplitOptions.RemoveEmptyEntries|StringSplitOptions.TrimEntries);
+            => str.IsNullOrEmpty() ? Array.Empty<string>() : str.Split(splitChars.Length == 0 ? new char[] { ',','，',';','；','.','。' } : splitChars,StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
 
         /// <summary>
         /// 将字符串按格式转换为时间格式
@@ -48,7 +48,7 @@ namespace Falcon.SugarApi
         /// <param name="culture">区域特性.默认CultureInfo.InvariantCulture</param>
         /// <returns>时间</returns>
         public static DateTime ToDateTime(this string str,string dateTimeFormat = "",CultureInfo? culture = null) {
-            culture??=CultureInfo.InvariantCulture;
+            culture ??= CultureInfo.InvariantCulture;
             if(dateTimeFormat.IsNullOrEmpty()) {
                 return DateTime.Parse(str);
             }
@@ -64,11 +64,11 @@ namespace Falcon.SugarApi
         /// <returns>成功True，失败False</returns>
         public static bool TryToDateTime(this string str,string dateTimeFormat,out DateTime dt,CultureInfo? culture = null) {
             try {
-                dt=str.ToDateTime(dateTimeFormat,culture);
+                dt = str.ToDateTime(dateTimeFormat,culture);
                 return true;
             }
             catch(Exception) {
-                dt=default;
+                dt = default;
                 return false;
             }
         }
@@ -112,18 +112,18 @@ namespace Falcon.SugarApi
         /// <returns>子字符串</returns>
         /// <exception cref="Exception">获取长度不满足要求</exception>
         public static string SubstringEx(this string str,int start,int length) {
-            if(start>str.Length||length==0) {
+            if(start > str.Length || length == 0) {
                 return "";
             }
-            if(length<0) {
+            if(length < 0) {
-                start=start+length;
+                start = start + length;
-                length=-length;
+                length = -length;
             }
-            if(start<0) {
+            if(start < 0) {
-                length+=start;
+                length += start;
-                start=0;
+                start = 0;
             }
-            if(start+length>str.Length) {
+            if(start + length > str.Length) {
                 return str.Substring(start);
             }
             return str.Substring(start,length);
@@ -136,17 +136,50 @@ namespace Falcon.SugarApi
         /// <param name="length">分割长度</param>
         /// <returns>分割后的字符串枚举</returns>
         public static IEnumerable<string> Split(this string str,int length) {
-            if(length<=0) {
+            if(length <= 0) {
                 throw new Exception("分割长度必须大于0");
             }
             if(str.IsNullOrEmpty()) {
                 throw new ArgumentNullException(nameof(str));
             }
             int i = 0;
-            while(str.Length>i) {
+            while(str.Length > i) {
                 yield return str.SubstringEx(i,length);
-                i+=length;
+                i += length;
             }
         }
+
+        /// <summary>
+        /// 从字符串开头去除startStr字符串并从末尾去除endStr字符串，如果有多个会全部去除。
+        /// </summary>
+        /// <param name="str">原始字符串</param>
+        /// <param name="startStr">开始处要去除的字符串，不需要则传入空字符串</param>
+        /// <param name="endStr">末尾处要去除的字符串，不需要则传入空字符串</param>
+        /// <returns>结果字符串</returns>
+        public static string TrimString(this string str,string startStr = "",string endStr = "") {
+            if(str == "") {
+                return str;
+            }
+            if(startStr != "") {
+                while(true) {
+                    var p = str.IndexOf(startStr);
+                    if(p < 0) {
+                        break;
+                    }
+                    str = str.Substring(p + startStr.Length);
+                }
+            }
+            if(endStr != "") {
+                while(true) {
+                    var p = str.LastIndexOf(endStr);
+                    if(p < 0) {
+                        break;
+                    }
+                    str = str.Substring(0,p);
+                }
+            }
+            return str;
+        }
+
     }
 }