This function is similar to strcmp(), with the difference that you can specify the (upper limit of the) number of characters (len) from each string to be used in the comparison.
Returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal.
Note that this comparison is case sensitive.
See also ereg(), strncasecmp(), strcasecmp(), substr(), stristr(), strcmp(), and strstr().