sub body { ... your code ...}

SWITCH: {
    body, last SWITCH if $wrongDateFlag and $#ARGV >= 2;
    body, last SWITCH if not $wrongDateFlag and $#ARGV >=2 and $oneDayFlag == -1
;
    body, last SWITCH if not $wrongDateFlag and $#ARGV >=1 and $oneDayFlag >= 0;
    $felloff == 1;
}


##</code><code>##

sub body { ... your code ...}

body if $wrongDateFlag and $#ARGV >= 2
        or not $wrongDateFlag and $#ARGV >=2 
        or not $wrongDateFlag and $#ARGV >=1 and $oneDayFlag >= 0;