C varargs usage check: should a variadic function use va_arg() specifically to extract the last argument in the variable list — True or False?

Introduction / Context:
This statement probes understanding of how va_arg works. The macro does not “jump” to the last argument; it sequentially retrieves the next argument of a specified type from the variable argument list represented by a va_list.

Given Data / Assumptions:

• Variadic function signature such as void logf(int n, ...);
• Caller may pass an arbitrary number of arguments.

Concept / Approach:
va_arg(ap, T) returns the next argument of type T and advances the va_list state. It has no knowledge of how many arguments were passed; determining the count is up to the function (via an explicit count parameter, a sentinel value, or a format string). Thus, the claim that va_arg() is for “the last argument” is false.

Step-by-Step Solution:
Initialize with va_start(ap, last_named_param);Iterate: for (...){ value = va_arg(ap, expected_type); }Stop based on a known count or a sentinel condition.Finish with va_end(ap);

Verification / Alternative check:
Review any formatted print implementation strategy: it repeatedly calls va_arg for each conversion specifier, never “seeking to the last”.

Why Other Options Are Wrong:
Architecture width (32-bit) and parity of count are irrelevant. The mechanism is the same across platforms that conform to the C standard.

Common Pitfalls:
Misconstruing va_arg as random-access; it is strictly sequential. Passing mismatched types against the expected types is undefined behavior.

Final Answer:
False