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For example, given an implementation that supports 128-bit unsigned integers and provides a uint_fast128_t type, a programmer may define the following type:

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The following non-compliant code example reads am an unsigned long long value from standard input and stores the result in x, which is of a programmer-defined integer type.

#include <stdio.h>
/* ... */
mytypedef_t x;
/* ... */
if(scanf("%llu", &x) != 1) {
  /* handle error */
}

Resultantly, this This code could result in a buffer overflow, if the size of mytypedef_t is smaller than unsigned long long, or it may might result in an incorrect value if the size of mytypedef_t is larger than unsigned long long.

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