What Are Fixed Width Integer Types In Modern C++

In C++ development, integer variables can be decimal (base 10), octal (base 8) or hexadecimal (base 16). In addition to int, short int, long int, and long long int, there are fixed width integer types. Fixed-width integers are defined types with a fixed number of bits. In this post we will list them.

What are fixed width integer types in modern C++?

In addition to standard types in C++, there are fixed-width integers which are defined types in header <cstdint> with a fixed number of bits. Fixed-width integers are called as intN_t or intX_t integers where N or X represents number of bits reserved for that type. That means, these integer types guarantee a specific size in bits, and can be portable to any other platform. Mostly we use decimal variables which are in ranges from 0 to 4,294,967,295 but there are many different types of integers that allows developers use the memory wisely.

What are fixed width signed integer types in modern C++?

Fixed-width integers which are defined types in header <cstdint>, and these can be listed as below,

Here are signed with integer types:

Fixed Width Integer Types	Description
int8_t	8 bits signed integer type
int16_t	16 bits signed integer type
int32_t	32 bits signed integer type
int64_t	64 bits signed integer type

Here are signed integer types ‘fastest form’:

Fixed Width Integer Types	Description
int_fast8_t	8 bits fast signed integer type
int_fast16_t	16 bits fast signed integer type
int_fast32_t	32 bits fast signed integer type
int_fast64_t	64 bits fast signed integer type

Here are signed with integer types in ‘smallest form’:

Fixed Width Integer Types	Description
int_least8_t	8 bits smallest signed integer type
int_least16_t	16 bits smallest signed integer type
int_least32_t	32 bits smallest signed integer type
int_least64_t	64 bits smallest signed integer type

and there is also maximum-width signed integer type:

Fixed Width Integer Types	Description
intmax_t	integer type that has maximum-width

and a signed integer type that holds pointer:

Fixed Width Integer Types	Description
intptr_t	signed integer type that holds pointer

What are fixed width unsigned integer types in modern C++

If you are sure that your integer variable is a zero or a positive number, you can use an unsigned version that doubles the highest integer number which can be used in that variable.

Here are unsigned with integer types in general form:

Fixed Width Integer Types	Description
uint8_t	8 bits unsigned integer type
uint16_t	16 bits unsigned integer type
uint32_t	32 bits unsigned integer type
uint64_t	64 bits unsigned integer type

Here are unsigned with integer types in fastest form:

Fixed Width Integer Types	Description
uint_fast8_t	8 bits fast unsigned integer type
uint_fast16_t	16 bits fast unsigned integer type
uint_fast32_t	32 bits fast unsigned integer type
uint_fast64_t	64 bits fast unsigned integer type

Here are signed with integer types in smallest form:

Fixed Width Integer Types	Description
uint_least8_t	8 bits smallest unsigned integer type
uint_least16_t	16 bits smallest unsigned integer type
uint_least32_t	32 bits smallest unsigned integer type
uint_least64_t	64 bits smallest unsigned integer type

and there is also maximum-width unsigned integer type:

Fixed Width Integer Types	Description
uintmax_t	integer type that has maximum-width

and unsigned integer type that holds pointer:

Fixed Width Integer Types	Description
uintptr_t	unsigned integer type that holds pointer

If you are looking more about Integer constants there are more details about them, https://docwiki.embarcadero.com/RADStudio/Alexandria/en/Integer_Constants

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