Strncmp is a member function of C programming language string.h library.
int strncmp(const char * s1,const char * s2, size_t num);
strncmp scans the strings up to the first numth character.Returns 0 when the strings are equal, a negative integer when
s1 is less than
s2, or a positive integer if
s1 is greater than
s2, according to the lexicographical order.
Do-It-Yourself Turbo C++; Paul J. Perry; SAMS Publishing 1992