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Possibly more important than knowing the number of bits for a given type is knowing that <limitslimits.h>h defines macros that can be used to determine the integral ranges of the standard integer types for any conforming implementation. For example, UINT_MAX is the largest possible value of an unsigned int, and LONG_MIN is the smallest possible value of a long int.

<stdint.h>

The <stdintstdint.h>h header introduces types with specific size restrictions that can be used to avoid dependence on a particular data model. For example, int_least32_t is the smallest signed integer type supported by the implementation that contains at least 32 bits. The type uint_fast16_t is the fastest unsigned integer type supported by the implementation that contains at least 16 bits. The type intmax_t is the largest signed integer, and uintmax_t is the largest unsigned type, supported by the implementation. The following types are required to be available on all implementations.

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Additional types may be supported by an implementation, such as int8_t, a type of exactly 8 bits, and uintptr_t, a type large enough to hold a converted void *, if such an integer exists in the implementation.

<inttypes.h>

The <inttypesinttypes.h>h header declares functions for manipulating greatest-width integers and converting numeric character strings to greatest-width integers.

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Understanding the data model used by your implementation is necessary to avoid making errors about the sizes of integer types and the range of values that they can represent. Making assumptions about the sizes of data types may lead to buffer-overflow-style attacks.

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