strncmp - compare part of two strings
#include <string.h> int strncmp(const char *s1, const char *s2, size_t n);
The strncmp() function compares not more than n bytes (bytes that follow a null byte are not compared) from the array pointed to by s1 to the array pointed to by s2.
The sign of a non-zero return value is determined by the sign of the difference between the values of the first pair of bytes (both interpreted as type unsigned char) that differ in the strings being compared.
Upon successful completion, strncmp() returns an integer greater than, equal to or less than 0, if the possibly null-terminated array pointed to by s1 is greater than, equal to or less than the possibly null-terminated array pointed to by s2 respectively.
No errors are defined.
Derived from Issue 1 of the SVID.