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This solution is in accordance with INT18-C. Evaluate integer expressions in a larger size before comparing or assigning to that size.

Noncompliant Code Example (memset())

For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char.  This can result in a unexpected behavior if the value cannot be represented in the smaller type.  This noncompliant solution unexpectedly clears the array.

#include <string.h>  #include <stddef.h>  #include <limits.h>  int *init_memory(int *array, size_t n) {  return memset(array, 4096, n); } 

Compliant Solution (memset())

In general, the memset() function should not be used to initialize an integer array unless it is to set or clear all the bits.

#include <string.h>  #include <stddef.h>  #include <limits.h>  int *init_memory(int *array, size_t n) {  return memset(array, 0, n); } 

Exceptions

INT31-EX1: The C Standard defines minimum ranges for standard integer types. For example, the minimum range for an object of type unsigned short int is 0 to 65,535, whereas the minimum range for int is −32,767 to +32,767. Consequently, it is not always possible to represent all possible values of an unsigned short int as an int. However, on the IA-32 architecture, for example, the actual integer range is from −2,147,483,648 to +2,147,483,647, meaning that it is quite possible to represent all the values of an unsigned short int as an int for this architecture. As a result, it is not necessary to provide a test for this conversion on IA-32. It is not possible to make assumptions about conversions without knowing the precision of the underlying types. If these tests are not provided, assumptions concerning precision must be clearly documented, as the resulting code cannot be safely ported to a system where these assumptions are invalid. A good way to document these assumptions is to use static assertions (see DCL03-C. Use a static assertion to test the value of a constant expression).

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