Online Upper Case Converter

Here is what I want to do but doesn't work:

mystring = "hello world"toUpper = ['a', 'e', 'i', 'o', 'u', 'y']array = list(mystring)for c in array:    if c in toUpper:        c = c.upper()print(array) 

"e" and "o" are not uppercase in my array.

What is the idiomatic and most effecient way to check if a single character in Elisp is lowercase, uppercase, alphanumeric, digit, whitespace, or any other similar character category? For example Python has string methods like isdigit(), but converting a character (which is just a number) to a string in Elisp to check if it belongs to a certain case or category seems like a wrong approach:

(string-match-p "[[:lower:]]" (char-to-string ?a))

What is an easy way in Golang to check if all characters in a string are upper case or lower case?

Also, how to handle a case where the string has punctuation?

See these examples:

package mainimport (    "fmt"    "unicode")func main() {    s := "UPPERCASE"    fmt.Println(s.IsUpper())  // Should print true    s = "lowercase"    fmt.Println(s.IsUpper())  // Should print false    s = "lowercase"    fmt.Println(s.IsLower())  // Should print true    s = "I'M YELLING AT YOU!"    fmt.Println(s.IsUpper())  // Should print true}

Note: s.IsUpper() and s.IsLower() doesn't really exist, but would be nice to find an equivalent.

I am new in regular expression. I want to remove a uppercase letter if it has lowercase before and after it. If the input is "I wilYl go theXre" then the output should be "I will go there". How can I get it?

I want to make the text that a user is typing into a textbox become uppercase. I know two ways to do this, which are:

Textbox1.Text = UCase(Textbox1.Text)orTextbox1.Text = Textbox1.Text.ToUpper

HOWEVER: both have the same problem (when embedded in a Textbox1_TextChanged event handler), which is that the cursor keeps being moved back to the start, so if you slowly type in, say abcdef, it comes out as FEDCBA. Is there a way to move the cursor back to the end of the string after each time it works to make the text uppercase?