Why Does Golang\'s Scanf Function Fail on Windows But Work on Mac?

GOLang Scanf Error: Why It Fails on Windows and Not on Mac

Seeking user input is a common task in programming. In GOLang, the Scanf function is often used for this purpose. However, a peculiar issue arises when using Scanf twice: it works on macOS but not on Windows.

In the provided code snippet:

<code class="go">func credentials() (string, string) {

    var username string
    var password string

    fmt.Print("Enter Username: ")
    fmt.Scanf("%s", &username)

    fmt.Print("Enter Password: ")
    fmt.Scanf("%s", &password)

    return username, password
}</code>

When run on macOS, the program prompts the user for their username and then password, as expected. However, on Windows, after prompting for the username, the program ignores the password prompt and abruptly exits.

The reason for this discrepancy lies in the way Scanf interprets user input. On Windows, Scanf uses carriage return (r) as the default line terminator, whereas macOS uses new line (n). When the username is entered and the user presses Enter, Scanf encounters the carriage return and interprets it as the input terminator. As a result, the program skips the second Scanf line and exits.

To resolve this issue on Windows, we can use Bufio, a library that provides buffering for I/O operations. Bufio offers an alternative to Scanf that is more robust and works consistently across operating systems. Here's a modified version of the code using Bufio:

<code class="go">func credentials() (string, string) {
    reader := bufio.NewReader(os.Stdin)

    fmt.Print("Enter Username: ")
    username, _ := reader.ReadString('\n')

    fmt.Print("Enter Password: ")
    password, _ := reader.ReadString('\n')

    return strings.TrimSpace(username), strings.TrimSpace(password) // ReadString() leaves a trailing newline character
}</code>

This version uses ReadString to read input from the user. ReadString accepts a delimiter, in this case the new line character 'n'. This ensures that both username and password are properly read even on Windows, as the line terminator is correctly handled.

In summary, Scanf exhibits inconsistent behavior on different operating systems, which can be attributed to differing line termination conventions. By using Bufio, developers can overcome these inconsistencies and rely on a more reliable method for capturing user input across various platforms.

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