undefined functions strlen sco 5.0.4

on sco 5.0.4 strings libphp4.so | grep strlen zend_if___std_hdr_strlen strlen __std_hdr_strlen strlen zend_if___std_hdr_strlen on linux redhat 6.2 strings libphp4.so | grep strlen strlen strlength strlen strlength the symbol str length is defined in both cases but on sco using the php function strlen results in undefined function error. looks like its defined. i saw an answer in php-dev email search that adding an underscore to the front may solve the problem, tried didnt work, looked to see if it was a macro definition as sugjested. /usr/include/strings.h defines it as extrn size_t strlen(const char *) any other ideas as where to look to solve this problem, i don't believe this is the only problem i think there maybe another having to do with opendir, readdir because my dir listing, file listing fuctions dont work on sco either, dont know if this info is releated. current work around for strlen i guess is to define a function in local.inc called strlen see if i can get it to work, for opendir read dir, arg exec('ls *')????? -- My opinions are my own and not that of my employer even if I am self employed