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This Go code demonstrates the use of the panic function, which is used to terminate the normal execution flow of a program and initiate a panic. Let's go through the code with inline comments and explanations:
// Importing necessary package.
import "os"
// The main function, where the execution of the program begins.
func main() {
// Initiating a panic with a custom error message.
panic("a problem")
// The code below this line will not be executed due to the preceding panic.
// Attempting to create a file (this code will not be reached).
_, err := os.Create("/tmp/file")
// Checking if an error occurred during file creation (this code will not be reached).
if err != nil {
// Initiating a panic with the error message if an error is present.


panic: a problem
goroutine 1 [running]:
..:/...../..../..../panic.go:7 +0x25
exit status 2
  1. 1.
    panic("a problem"):
    • This line explicitly triggers a panic with the message "a problem."
    • When a panic occurs, the normal flow of the program is halted, and the program terminates abruptly.
  2. 2.
    _, err := os.Create("/tmp/file"):
    • This line attempts to create a file in the "/tmp" directory.
    • Note that this line and the subsequent lines will not be executed if a panic occurs earlier in the code.
  3. 3.
    if err != nil { panic(err) }:
    • This code checks if an error occurred during the file creation process (which will not happen in this example due to the preceding panic).
    • If an error is present, it triggers another panic with the error message.
It's important to note that initiating a panic is typically used in exceptional situations where the program cannot continue normal execution. In general, using panics should be done judiciously, and it's often preferable to handle errors in a more controlled manner using error values and other error-handling techniques.