The given index must be a non-negative integer less than the length of string, which must be a string. The character at position index of the string is returned as a character object.

As with all sequences in Common Lisp, indexing is zero-origin. For example:

See aref and elt. In effect,

setf may be used with char to destructively replace a character within a string.

For char, the string may be any string; for schar, it must be a simple string. In some implementations of Common Lisp, the function schar may be faster than char when it is applicable.