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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