Writing Apache Modules with Perl and C

11.3. String and URI Manipulation

The Apache API provides an extensive set of functions for parsing and manipulating strings and URIs. Some of these routines are functionally identical to standard C library functions but provide either a performance boost or enhanced safety. Other routines provide completely new functionality.

11.3.1. String Parsing Functions

While Apache's library for parsing and manipulating character strings is not nearly as rich as Perl's text processing abilities, it is a vast improvement over what's available in the impoverished standard C library.

Most of the string parsing routines belong to the ap_getword* family, which together provide functionality similar to the Perl split() function. Each member of this family is able to extract a word from a string, splitting the text on delimiters such as whitespace or commas. Unlike Perl split(), in which the entire string is split at once and the pieces are returned in a list, the ap_getword* functions operate on one word at a time. The function returns the next word each time it's called and keeps track of where it's been by bumping up a pointer.

All of the ap_getword* routines are declared in httpd.h. The original declarations in httpd.h refer to the second argument as char **line. In the function prototypes that follow, we've changed the name of this argument to char **string in order to avoid the implication that the argument must always correspond to a single line of text.

char *ap_getword (pool *p, const ...