Fixed string length check into SetStringAt

- fix #28

CHANGELOG.md

@@ -1,6 +1,12 @@
 # Change Log
 All notable changed to this project will be documented in this file.
 
+## [1.1.82] - 18.05.2022
+### Added
+### Changed
+### Fixed
+- Fixed string length check into SetStringAt [#28](https://github.com/fbarresi/Sharp7/issues/28)
+
 ## [1.1.81] - 18.05.2022
 ### Added
 ### Changed

Sharp7.Tests/TestUtilities.cs

@@ -337,11 +337,12 @@ namespace Sharp7.Tests
         }
 
         [Theory]
-        [InlineData("888", new byte[] {200, 3, 56,56,56})]
-        public void TestSetStringAt(string test, byte[] expected)
+        [InlineData("888", 200, new byte[] {200, 3, 56,56,56})]
+        [InlineData("888888", 5, new byte[] {5, 5, 56,56,56,56,56})]
+        public void TestSetStringAt(string test, int maxLength, byte[] expected)
         {
-            var buffer = new byte[200];
-            S7.SetStringAt(buffer, 0, buffer.Length, test);
+            var buffer = new byte[maxLength+2];
+            S7.SetStringAt(buffer, 0, maxLength, test);
             buffer.Take(expected.Length).ToArray().ShouldBe(expected);
         }
         

Sharp7/S7.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 
 namespace Sharp7
@@ -615,10 +616,12 @@ namespace Sharp7
 
         public static void SetStringAt(this byte[] buffer, int pos, int MaxLen, string value)
         {
-            int size = value.Length;
+            int length = value.Length;
+            // checking current length against MaxLen
+            if (length > MaxLen) length = MaxLen;
             buffer[pos] = (byte) MaxLen;
-            buffer[pos + 1] = (byte) size;
-            Encoding.UTF8.GetBytes(value, 0, size, buffer, pos + 2);
+            buffer[pos + 1] = (byte) length;
+            Encoding.UTF8.GetBytes(value, 0, length, buffer, pos + 2);
         }
 
         #endregion