2.3.9 const char * strchrnul_P

const char * strchrnul_P(const char *, int __val)

The strchrnul_P() function is like strchr_P() except that if c is not found in s, then it returns a pointer to the null byte at the end of s, rather than NULL. (Glibc, GNU extension.)

Remember:

The strchrnul_P() function returns a pointer to the matched character, or a pointer to the null byte at the end of s (i.e., s+strlen(s)) if the character is not found.