2.6. Strings

2.6. Strings
Prev	Chapter 2. Manipulating Lisp objects	Next

A string, both in Common-Lisp and in ECL is nothing but a vector of characters. Therefore, almost everything mentioned in the section of arrays remains valid here. The only important difference is that ECL stores strings as a lisp object with a pointer to a zero terminated C string. Thus, if a string has n characters, ECL will reserve n+1 bytes for the string. This allows us to pass the string self pointer to any C routine.

If x is a lisp object of type string, we can access the following fields:

`x->string.dim`	Maximum number of characters that it can contain.
`x->string.fillp`	Actual number of characters in the string.
`x->string.self`	Pointer to the characters.
`x->string.hasfillp`	True if `x->string.fillp` can be smaller than `x->string.dim`.

 Function: cl_object make_simple_string (char *s)
 Function: cl_object make_string_copy (char *s)
Both routines build a lisp string from a C string. make_string_copy allocates new space and copies the content of the string to it. make_simple_string simply uses the memory pointed by s, which should not be deallocated. Both routines use strlen to calculate the length of the string.

Prev	Up	Next
2.5. Arrays	Home	2.7. Bitvectors