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C++ Language/Std/Strings/AvoidingBufferOverrun
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Some of the original C-Runtime functions were succeptible to a buffer-overrun-hack.
For example, strnlen(NULL, 16) would cause a runtime-error.
A safer alternative is available in Win32; strnlen_s(NULL, 16) simply returns 0 without trying to overrun the buffer.
Additional information about avoiding buffer-overrun