C strings: which standard library function finds the last occurrence of a character in a string? Pick the correct function name used to search from the end.

Introduction / Context:
This question assesses knowledge of common string functions in the C standard library, specifically how to locate characters within a NUL-terminated byte string.

Given Data / Assumptions:

• The target is to find the last occurrence of a given character.
• Input is a standard C string terminated by a '\\0' byte.
• We want the standard function provided by string.h.

Concept / Approach:

The correct function is strrchr(const char *s, int c). It searches for the last occurrence of c (converted to unsigned char) in the string s, including the terminating '\\0' if c is '\\0'. It returns a pointer to the located character or NULL if not found.

Step-by-Step Solution:

Verification / Alternative check:

Compare with strchr which finds the first occurrence; the extra 'r' in strrchr mnemonically stands for “reverse/last”.

Why Other Options Are Wrong:

strnchar, strchar, strrchar: These are not standard C functions.

Common Pitfalls:

• Confusing strchr and strrchr.
• Forgetting that searching for '\\0' is allowed and returns a pointer to the terminator.

Final Answer:

strrchr()