how can you check if a string has no repeating charachters without using any function or adding extra variables. So With only one variable that would get the input from the user and the use of for loops
I am not entirely sure what you are trying to achieve exactly. Could you be more specific? Maybe giving us an example?
When you say "no repeating characters" do you mean something like this:
"this is a string"would fail validation as it contains three
sas well as two