Perhaps use case/esac with a pattern of [a-z]+

Try this:
Not exactly sure what you want your end result to be - but this for instance should find uppercase letters - if they are there, convert them to lowercase.
Basically, doing the grep for [A-Z] returns the argument provided if it has capital letters. If this happens, the return code ($?) is 0. If the return code is a 1, no capital letters were in the argument.
You can then run through all arguments.

You can apply this anyway you want though. Grep for [a-z] or [A-Z]. If the return code is 0, then the caps or lowercase were found and you can act accordingly.

thanks omrsafetyo!!!

i would like to know wheather is there a way thats i can check multiple arguments at the same time? bcos i got 3 args to input then i would like to check this 3 args for uppercase.

with my above function:

... or

if you want something simpler.

You could, for instance, rewrite the test_upper function to return a 1 or a 0, depending on whether or not it found uppercase. (You could simple use "echo $?" to "return" this value). Then, when you loop the arguments, you can have a variable that holds whether or not the case you are testing for was found (globally). e.g.

Look at the bash guide here. It has examples on checking for upper case.