regular expressions

[YaNuSH]

how do i check whether a certain string contains only capital letters and numbers?
how do i check whether the 4th character in a string is a number?
i heard u can do all these with regular expressions but unfortunately i have no idea how to use them

[ppslim]

You can do it with regular expressions and Tcl (version dependant)

This should work however.

proc is_only_cap_and_num {t} {
regsub -all -- {[A-Z0-9]} $t "" t
if {$t == ""} { return 1 }
return 0
}

Will return 1 is it is only capc or numbers - no spaces, lower case or any other character allowed.

proc is_4th_char_a_num {t} {
regsub -aa -- {[0-9]} [string index $t 3] "" t
if {$t == ""} { return 1 }
return 0
}

Will return 1 with the 4th character is a number.

Both can be done in Tcl, but can be long winded.

[YaNuSH]

ty very much. that worked. u really helped me alot.