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In the following code example, the variadic function {{average()}} is used to determine the average value of its passed positive integer arguments \[[Seacord 05c|AA. C References#Seacord 05c]\]. The function processes arguments until it finds one with a value of {{\-1}}, AKA {{va_eol}}. |
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enum {va_eol = -1}; unsigned int average(int first, ...) { size_t count = 0; unsigned int sum = 0; int i = first; va_list markerargs; va_start(markerargs, first); while (i != -1va_eol) { sum += i; count++; i = va_arg(markerargs, int); } va_end(markerargs); return(count ? (sum / count) : 0); } |
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int avg = average(1, 4, 6, 4, 1); |
The omission of the -1 va_eol terminating value means that the function will continue to process values from the stack until it encounters a -1 va_eol by coincidence or an error occurs.
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The following call maintains the contract by adding a -1 va_eol as the last argument.
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int avg = average(1, 4, 6, 4, 1, -1va_eol); |
Non-Compliant Code Example
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