did you mean swap(&a
do you understand what {9999} did?
you have an array with {9999,0,0,0} is this your intent?
are you trying to swap digits? its really unclear.
the letters will escape to the farthest values with ascii code.
Example my password abcd.For example my password is ABCD. if the hacker approaches my password, thanks to ascii code will be missed Will be 9876