Golang : flag provided but not defined error




Problem :

Your program uses flag.Parse() function to parse the command line arguments and everything is working fine until you attempted to parse a negative value, For example, such as calculating quadratic equation.

./program -3.0 1.0

This will cause the flag.Parse() function to recognize it a flag parameter instead of negative value. How to fix this?

Solution :

Use os.Args instead of flag.Parse. For example, change

 flag.Parse()
 arg := flag.Arg(0)

to

 arg := os.Args[1]

Happy coding and hope this helps!

  See also : Golang : Get command line arguments



Tags : golang flag-provided parse-flag

Adam Ng By Adam Ng

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