demo1.txt founded in the root directory same place with main.go and error handling explained

error_handling/demo1.go

@@ -0,0 +1,50 @@
+/**
+
+error handling - trying to open a file which does not exist
+  
+BSD 3-Clause License
+
+Copyright (c) 2024 Mass Collaboration Labs and contributors
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+  
+ **/
+package error_handling
+
+import "os"
+import "fmt"
+
+
+func Demo1(){
+	f, err := os.Open("demo1.txt")
+	if err!=nil{
+		fmt.Println("File does not exist")
+	}else{
+		fmt.Println(f.Name())
+	}
+	
+}
+

error_handling/demo1.go~

@@ -0,0 +1,2 @@
+package error_handling
+

main.go

@@ -17,6 +17,7 @@ import (
 	"golesson/structs"
 	"golesson/variables"
 	"time"
+	"golesson/error_handling"
 )
 
 func main() {
@@ -84,4 +85,6 @@ func main() {
 	defer_statement.B()
 	defer_statement.Test()
 	defer_statement.Demo3()
+
+	error_handling.Demo1()
 }