Introduction

In Lua, converting a string to uppercase can be done using the string.upper() function. This function takes a string as input and returns a new string with all the letters converted to uppercase. Here’s an example:

local str = ""hello world""
local uppercaseStr = string.upper(str)
print(uppercaseStr) -- Output: HELLO WORLD

In the code snippet above, we define a variable str and assign it the value ““hello world””. We then use the string.upper() function to convert str to uppercase and store the result in a new variable uppercaseStr. Finally, we use the print() function to display the uppercase string.

It’s worth noting that the string.upper() function only converts alphabetic characters to uppercase. Non-alphabetic characters, such as numbers or symbols, will remain unchanged. For example:

local str = ""123abc!@#""
local uppercaseStr = string.upper(str)
print(uppercaseStr) -- Output: 123ABC!@#

In this case, the string ““123abc!@#”” is not modified by the string.upper() function because it contains characters that are not alphabetic.

If you want to ensure that all characters in a string are converted to uppercase, including non-alphabetic ones, you can use a loop to iterate over each character and convert it individually. Here’s an example:

local str = ""123abc!@#""
local uppercaseStr = """"
for i = 1, #str do
  local char = string.sub(str, i, i)
  local uppercaseChar = string.upper(char)
  uppercaseStr = uppercaseStr .. uppercaseChar
end
print(uppercaseStr) -- Output: 123ABC!@#

In this code snippet, we initialize an empty string uppercaseStr and then use a loop to iterate over each character in str. The string.sub() function is used to extract each character at the current index i, and the string.upper() function is used to convert the character to uppercase. The uppercase character is then appended to uppercaseStr using the concatenation operator ... After the loop finishes, uppercaseStr contains the desired uppercase string.

I hope you found this tutorial helpful!