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Few programmers consider the issues around formatted I/O and type definitions. A programmer-defined integer type might be any type supported by the implementation, even a type larger than unsigned long long.

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mytypedef_t x;
uintmax_t temp;

temp = x; /* alwaysAlways secure*/

/* ... changeChange the value of temp ... */

if (temp <= MYTYPEDEF_MAX) {
  x = temp;
}

...

In addition to programmer-defined types, there is no requirement that an implementation provide format-length modifiers for implementation-defined integer types. For example, a machine with an implementation-defined 48-bit integer type may not provide format-length modifiers for the type. Such a machine still must have a 64-bit long long, with intmax_t being at least that large.

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Visual Studio 2012 and earlier versions do not support the standard  standard j length modifier or and do not have a nonstandard analogueanalog. Consequently, you the programmer must hard code the knowledge that intmax_t is int64_t and uintmax_t is uint64_t for Microsoft Visual Studio versions.

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#include <stdio.h>

mytypedef_t x;
/* ... */
if (scanf("%llu", &x) != 1) {
  /* handleHandle error */
}

This noncompliant code example can result in a buffer overflow if the size of mytypedef_t is smaller than unsigned long long, or it might result in an incorrect value if the size of mytypedef_t is larger than unsigned long long.

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#include <stdio.h>
#include <inttypes.h>

mytypedef_t x;
uintmax_t temp;

/* ... */

if (scanf("%ju", &temp) != 1) {
  /* handleHandle error */
}
if (temp > MYTYPEDEF_MAX) {
  /* handleHandle error */
}
else {
  x = temp;
} 

...

Visual Studio 2012 and earlier versions do not support the standard j length modifier or and do not have a nonstandard analogueanalog. Consequently, you the programmer must hard code the knowledge that intmax_t is int64_t and uintmax_t is uint64_t for Microsoft Visual Studio versions.

#include <stdio.h>
#include <inttypes.h>

mytypedef_t x;
uintmax_t temp;

/* ... */
#ifdef _MSC_VER
#  define UINTMAX_CS "%llu"
#else
#  define UINTMAX_CS "%ju"
#endif

if (scanf(UINTMAX_CS, &temp) != 1) {
 /* handleHandle error */
}
if (temp > MYTYPEDEF_MAX) {
  /* handleHandle error */
}
else {
  x = temp;
} 

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