type_0_1.rst

Types 0 & 1 – Positive and negative integers

CBOR has two types of integers – positive (which may be effectively regarded as unsigned), and negative. There are four possible widths for an integer – 1, 2, 4, or 8 bytes. These are represented by

cbor_int_width

Type 0 - positive integers

Corresponding cbor_type	CBOR_TYPE_UINT
Number of allocations	One per lifetime
Storage requirements	sizeof(cbor_item_t) + sizeof(uint*_t)

Note: once a positive integer has been created, its width cannot be changed.

Type 1 - negative integers

Corresponding cbor_type	CBOR_TYPE_NEGINT
Number of allocations	One per lifetime
Storage requirements	sizeof(cbor_item_t) + sizeof(uint*_t)

Note: once a positive integer has been created, its width cannot be changed.

Type 0 & 1

Due to their largely similar semantics, the following functions can be used for both Type 0 and Type 1 items. One can convert between them freely using the conversion functions.

Actual Type of the integer can be checked using item types API <item-types>.

An integer item is created with one of the four widths. Because integers' storage is bundled together with the handle, the width cannot be changed over its lifetime.

Warning

Due to the fact that CBOR negative integers represent integers in the range [ − 1,  − 2^N], cbor_set_uint API is somewhat counter-intuitive as the resulting logical value is 1 less. This behavior is necessary in order to permit uniform manipulation with the full range of permitted values. For example, the following snippet

cbor_item_t * item = cbor_new_int8();
cbor_mark_negint(item);
cbor_set_uint8(0);

will produce an item with the logical value of  − 1. There is, however, an upside to this as well: There is only one representation of zero.

Building new items

cbor_build_uint8

cbor_build_uint16

cbor_build_uint32

cbor_build_uint64

Retrieving values

cbor_get_uint8

cbor_get_uint16

cbor_get_uint32

cbor_get_uint64

Setting values

cbor_set_uint8

cbor_set_uint16

cbor_set_uint32

cbor_set_uint64

Dealing with width

cbor_int_get_width

Dealing with signedness

cbor_mark_uint

cbor_mark_negint

Creating new items

cbor_new_int8

cbor_new_int16

cbor_new_int32

cbor_new_int64