strncmp - compare part of two strings
int strncmp(const char *s1, const char *s2, size_t n);
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.
The strncmp() function shall compare not more than n bytes (bytes that follow a NUL character 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() shall return 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.
First released in Issue 1. Derived from Issue 1 of the SVID.
Extensions beyond the ISO C standard are marked.
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