diff --git a/main.go b/main.go
index c8a856b..4433889 100644
--- a/main.go
+++ b/main.go
@@ -50,6 +50,7 @@ import (
 	"golesson/maps"
 	"golesson/pointers"
 	"golesson/slices"
+	"golesson/string_functions"
 	"golesson/structs"
 	"golesson/variables"
 	"time"
@@ -125,4 +126,5 @@ func main() {
 	interfaces.Demo3()
 	error_handling.Demo2()
 	fmt.Println(error_handling.GuessIt2(102))
+	string_functions.Demo1()
 }
diff --git a/string_functions/demo1.go b/string_functions/demo1.go
new file mode 100644
index 0000000..395bb19
--- /dev/null
+++ b/string_functions/demo1.go
@@ -0,0 +1,26 @@
+package string_functions
+
+//alias
+import (
+	"fmt"
+	s "strings"
+)
+
+// case sensitive
+// ascii
+func Demo1() {
+	name := "Engin"
+	fmt.Println(s.Count(name, "g"))
+	fmt.Println(s.Contains(name, "g"))
+	fmt.Println(s.Index(name, "g"))
+	result := s.Index(name, "E")
+
+	if result != -1{
+		fmt.Println("E letter exists")
+	}else{
+		fmt.Println("E letter does not exist")
+	}
+
+	fmt.Println(s.ToLower(name))
+	fmt.Println(s.ToUpper(name))
+}