From 402be3d385610cb5b7d83da738f84da3f3b0c380 Mon Sep 17 00:00:00 2001
From: Nikitin Aleksandr <nikitinav@atomsbt.ru>
Date: Thu, 14 Nov 2024 14:49:44 +0300
Subject: [PATCH] =?UTF-8?q?=D1=81=D0=B4=D0=B5=D0=BB=D0=B0=D0=BB=20msg.Pars?=
 =?UTF-8?q?eMode=20=3D=20"HTML"?=
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---
 micro/microfunctions.go      | 15 +++++++++++++++
 micro/microfunctions_test.go | 22 ++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/micro/microfunctions.go b/micro/microfunctions.go
index 1ac128cb..82517254 100644
--- a/micro/microfunctions.go
+++ b/micro/microfunctions.go
@@ -1215,3 +1215,18 @@ func MassFrom_Map[C constraints.Ordered, V any](Map map[C]V) []V {
 
 	return Otvet
 }
+
+// Substring - take at most last n characters, from start index
+func Substring(input string, StartIndex int, length int) string {
+	asRunes := []rune(input)
+
+	if StartIndex >= len(asRunes) {
+		return ""
+	}
+
+	if StartIndex+length > len(asRunes) {
+		length = len(asRunes) - StartIndex
+	}
+
+	return string(asRunes[StartIndex : StartIndex+length])
+}
diff --git a/micro/microfunctions_test.go b/micro/microfunctions_test.go
index 479fac1d..1717e943 100644
--- a/micro/microfunctions_test.go
+++ b/micro/microfunctions_test.go
@@ -1206,3 +1206,25 @@ func TestStringDateTime(t *testing.T) {
 		t.Errorf("Test case 2 failed. Expected: %s, Got: %s", expectedResult2, result2)
 	}
 }
+
+func TestSubstring(t *testing.T) {
+	tests := []struct {
+		input       string
+		startIndex  int
+		length      int
+		expected    string
+		description string
+	}{
+		{"hello", 0, 2, "he", "Getting the first 2 characters"},
+		{"world", 2, 3, "rld", "Getting characters from index 2 to 4"},
+		{"test", 5, 2, "", "Start index beyond the length of the string"},
+		{"", 0, 2, "", "Empty input string"},
+	}
+
+	for _, test := range tests {
+		result := Substring(test.input, test.startIndex, test.length)
+		if result != test.expected {
+			t.Errorf("Test case failed: %s. Expected: %s, but got: %s", test.description, test.expected, result)
+		}
+	}
+}