新增字符串扩展方法SubstringEx和Split方法。

Falcon.SugarApi.Test/StringExtendTest.cs

@@ -1,4 +1,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MySqlX.XDevAPI.Common;
+using System;
+using System.Linq;
 
 namespace Falcon.SugarApi.Test
 {
@@ -13,31 +16,31 @@ namespace Falcon.SugarApi.Test
         public void TestSplit() {
             var str = $"a,b.c;d，e。f；g";
             var strArr = str.SplitStr();
-            Assert.AreEqual(7, strArr.Length, "分割后长度应该为7");
+            Assert.AreEqual(7,strArr.Length,"分割后长度应该为7");
             str = "a,,,    ,b    ,c    c,";
             strArr = str.SplitStr();
-            Assert.AreEqual(3, strArr.Length, "分割后长度应该为3");
+            Assert.AreEqual(3,strArr.Length,"分割后长度应该为3");
-            Assert.AreEqual("a", strArr[0]);
+            Assert.AreEqual("a",strArr[0]);
-            Assert.AreEqual("b", strArr[1]);
+            Assert.AreEqual("b",strArr[1]);
-            Assert.AreEqual("c    c", strArr[2]);
+            Assert.AreEqual("c    c",strArr[2]);
             str = null;
             strArr = str.SplitStr();
             Assert.IsNotNull(strArr);
-            Assert.AreEqual(0, strArr.Length);
+            Assert.AreEqual(0,strArr.Length);
 
             //指定分隔符
             str = $"a,b.c;d，e。f；g";
 
             strArr = str.SplitStr(',');
-            Assert.AreEqual(2, strArr.Length, "分割后长度应该为7");
+            Assert.AreEqual(2,strArr.Length,"分割后长度应该为7");
-            Assert.AreEqual("a", strArr[0]);
+            Assert.AreEqual("a",strArr[0]);
-            Assert.AreEqual("b.c;d，e。f；g", strArr[1]);
+            Assert.AreEqual("b.c;d，e。f；g",strArr[1]);
 
-            strArr = str.SplitStr(',', '.');
+            strArr = str.SplitStr(',','.');
-            Assert.AreEqual(3, strArr.Length, "分割后长度应该为7");
+            Assert.AreEqual(3,strArr.Length,"分割后长度应该为7");
-            Assert.AreEqual("a", strArr[0]);
+            Assert.AreEqual("a",strArr[0]);
-            Assert.AreEqual("b", strArr[1]);
+            Assert.AreEqual("b",strArr[1]);
-            Assert.AreEqual("c;d，e。f；g", strArr[2]);
+            Assert.AreEqual("c;d，e。f；g",strArr[2]);
         }
 
         /// <summary>
@@ -48,13 +51,67 @@ namespace Falcon.SugarApi.Test
             var str = "";
             var r = "";
             r = str.ToDefault("abc");
-            Assert.AreEqual("abc", r);
+            Assert.AreEqual("abc",r);
             str = null;
             r = str.ToDefault("abc");
-            Assert.AreEqual("abc", r);
+            Assert.AreEqual("abc",r);
             str = "123";
             r = str.ToDefault("abc");
-            Assert.AreEqual("123", r);
+            Assert.AreEqual("123",r);
+        }
+
+        /// <summary>
+        /// 检索子字符串测试
+        /// </summary>
+        [TestMethod]
+        public void TestSubstringEx() {
+            var str = "abcd33";
+            string r;
+            r = str.SubstringEx(str.Length + 1,1);
+            Assert.IsTrue(r == "");
+            r = str.SubstringEx(0,0);
+            Assert.IsTrue(r == "");
+            r = str.SubstringEx(3,-1);
+            Assert.IsTrue(r == "c");
+            r = str.SubstringEx(3,10);
+            Assert.IsTrue(r == "d33");
+            r = str.SubstringEx(-1,2);
+            Assert.IsTrue(r == "a");
+            r = str.SubstringEx(1,2);
+            Assert.IsTrue(r == "bc");
+
+        }
+
+        /// <summary>
+        /// 按一定长度分割字符串测试
+        /// </summary>
+        [TestMethod]
+        public void TestSplitByLength() {
+            string str;
+            string[] result;
+
+            str = "";
+            Assert.ThrowsException<ArgumentNullException>(() => { result = str.Split(5).ToArray(); });
+            str = "abc";
+            Assert.ThrowsException<Exception>(() => { result = str.Split(0).ToArray(); });
+            result = str.Split(1).ToArray();
+            Assert.IsTrue(result.Length == 3);
+            Assert.IsTrue(result[0] == "a");
+            Assert.IsTrue(result[1] == "b");
+            Assert.IsTrue(result[2] == "c");
+
+            result = str.Split(2).ToArray();
+            Assert.IsTrue(result.Length == 2);
+            Assert.IsTrue(result[0] == "ab");
+            Assert.IsTrue(result[1] == "c");
+
+            result = str.Split(3).ToArray();
+            Assert.IsTrue(result.Length == 1);
+            Assert.IsTrue(result[0] == "abc");
+
+            result = str.Split(4).ToArray();
+            Assert.IsTrue(result.Length == 1);
+            Assert.IsTrue(result[0] == "abc");
         }
     }
 }

Falcon.SugarApi/StringExtend.cs

@@ -1,6 +1,9 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
+using System.Linq;
+using System.Reflection.Metadata;
 
 namespace Falcon.SugarApi
 {
@@ -28,7 +31,7 @@ namespace Falcon.SugarApi
         /// <param name="str">字符串</param>
         /// <param name="defaultVal">默认值</param>
         /// <returns>字符串本身或默认值</returns>
-        public static string? ToDefault(this string? str, [NotNull] string defaultVal) => str.IsNullOrEmpty() ? defaultVal : str;
+        public static string? ToDefault(this string? str,[NotNull] string defaultVal) => str.IsNullOrEmpty() ? defaultVal : str;
 
         /// <summary>
         /// 使用全角半角的逗号句号和分号分割字符串。
@@ -36,8 +39,8 @@ namespace Falcon.SugarApi
         /// <param name="str">要分割的字符串</param>
         /// <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)
+        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>
@@ -47,12 +50,12 @@ namespace Falcon.SugarApi
         /// <param name="dateTimeFormat">时间格式</param>
         /// <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) {
+        public static DateTime ToDateTime(this string str,string dateTimeFormat = "",CultureInfo? culture = null) {
             culture ??= CultureInfo.InvariantCulture;
-            if (dateTimeFormat.IsNullOrEmpty()) {
+            if(dateTimeFormat.IsNullOrEmpty()) {
                 return DateTime.Parse(str);
             }
-            return DateTime.ParseExact(str, dateTimeFormat, culture);
+            return DateTime.ParseExact(str,dateTimeFormat,culture);
         }
         /// <summary>
         /// 尝试将特定格式字符串转换为DateTime类型
@@ -62,12 +65,11 @@ namespace Falcon.SugarApi
         /// <param name="dt">转换后的时间</param>
         /// <param name="culture">区域特性.默认CultureInfo.InvariantCulture</param>
         /// <returns>成功True，失败False</returns>
-        public static bool TryToDateTime(this string str, string dateTimeFormat, out DateTime dt, CultureInfo? culture = null) {
+        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) {
-            catch (Exception) {
                 dt = default;
                 return false;
             }
@@ -80,14 +82,64 @@ namespace Falcon.SugarApi
         /// <param name="dateFormat">日期时间格式</param>
         /// <returns>是True，否False</returns>
         /// <exception cref="ArgumentNullException">参数为空</exception>
-        public static bool IsDateFormat(this string str, string dateFormat) {
+        public static bool IsDateFormat(this string str,string dateFormat) {
-            if (str.IsNullOrEmpty()) {
+            if(str.IsNullOrEmpty()) {
                 throw new ArgumentNullException(nameof(str));
             }
-            if (dateFormat.IsNullOrEmpty()) {
+            if(dateFormat.IsNullOrEmpty()) {
                 throw new ArgumentNullException(nameof(dateFormat));
             }
-            return str.TryToDateTime(dateFormat, out var _);
+            return str.TryToDateTime(dateFormat,out var _);
+        }
+
+        /// <summary>
+        /// 获取子字符串
+        /// <para>如果start大于字符串长度或者length等于0则返回空字符串。</para>
+        /// <para>如果length小于0则返回start前面长度的字符串。</para>
+        /// <para>如果字符串不满足需要的长度要求则返回实际长度字符串。</para>
+        /// <para>如果start小于0，则返回从0开始的length+start长度字符串。</para>
+        /// </summary>
+        /// <param name="str">要检索的字符串</param>
+        /// <param name="start">开始位置</param>
+        /// <param name="length">获取长度</param>
+        /// <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) {
+                return "";
+            }
+            if(length < 0) {
+                start = start + length;
+                length = -length;
+            }
+            if(start < 0) {
+                length += start;
+                start = 0;
+            }
+            if(start + length > str.Length) {
+                return str.Substring(start);
+            }
+            return str.Substring(start,length);
+        }
+
+        /// <summary>
+        /// 按照固定长度分割字符串
+        /// </summary>
+        /// <param name="str">要分割的字符串</param>
+        /// <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) {
+                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) {
+                yield return str.SubstringEx(i,length);
+                i += length;
+            }
         }
     }
 }