regex switch

function Get-BobResponse() {
    [CmdletBinding()]
    Param(
        [string]$HeyBob
    )
    switch -Regex -CaseSensitive ($HeyBob.TrimEnd()) {
        "^[A-Z ]+\?$"           {"Calm down, I know what I'm doing!"; break}
        "^$"                    {"Fine. Be that way!"}
        "\?$"                   {"Sure."}
        "^[^a-z]*[A-Z][^a-z]*$" {"Whoa, chill out!"}
        Default                 {"Whatever."}
    }
}

We begin by trimming the input from the end, then use it as input for the switch statement with -Regex and -CaseSensitive flags to start matching against patterns. By default PowerShell will match insensitively, so the second flag is needed to check for the yelling condition.

    switch -Regex -CaseSensitive ($HeyBob.TrimEnd())

The first case we should consider is the combined conditions of both yelling and question. Which mean we should match for uppercase letter and space with at least one appearance, and a question martk at the end. We break out of the switch statement if this got a match.

    "^[A-Z ]+\?$"           {"Calm down, I know what I'm doing!"; break}

Then we can match individual cases that does not share conditions. silence pattern match nothing from beginning to end, question pattern match for a question mark at the end, and yelling match for uppercase letter. If none of the patterns got a match, then we return the default response.

    "^$"                    {"Fine. Be that way!"}
    "\?$"                   {"Sure."}
    "^[^a-z]*[A-Z][^a-z]*$" {"Whoa, chill out!"}
    Default                 {"Whatever."}

Note : This approach is not recommended for new learners.

Regex.