6.10.5 String Accessors & Modifiers

Function: string-length string

[R5RS] Returns a length of (possibly incomplete) string string.

Function: string-size string

Returns a size of (possibly incomplete) string. A size of string is a number of bytes string occupies on memory. The same string may have different sizes if the native encoding scheme differs.

For incomplete string, its length and its size always match.

Function: string-ref cstring k &optional fallback

[R5RS+] Returns k-th character of a complete string cstring. It is an error to pass an incomplete string.

By default, an error is signalled if k is out of range (negative, or greater than or equal to the length of cstring). However, if an optional argument fallback is given, it is returned in such case. This is Gauche's extension.

Function: string-byte-ref string k

Returns k-th byte of a (possibly incomplete) string string. Returned value is an integer in the range between 0 and 255. k must be greater than or equal to zero, and less than (string-size string).

Function: string-set! string k char

[R5RS] Substitute string's k-th character by char. k must be greater than or equal to zero, and less than (string-length string). Return value is undefined.

If string is an incomplete string, integer value of the lower 8 bits of char is used to set string's k-th byte.

See the notes in make-string about performance consideration.

Function: string-byte-set! string k byte

Substitute string's k-th byte by integer byte. byte must be in the range between 0 to 255, inclusive. k must be greater than or equal to zero, and less than (string-size string). If string is a complete string, it is turned to incomplete string by this operation. Return value is undefined.