Array elements have a base type
double a[4]; signed b[N]; The four elements of a are double objects, while the elements of b are signed objects. In a multidimensional declaration such as double C[M][N], C[0] is an array and C[0][0] is a double object. section 6.1.1
A basic type is one of C’s starting types for constructing derived types. Its first specification level uses keywords such as signed, int, and double; a second level uses semantic types supplied by headers, such as size_t and bool. Basic types represent unsigned integers, signed integers, real floating-point numbers, or complex floating-point numbers, with types differing in precision and permitted value range. section 5.2
Important rules distinguish basic types from their use in expressions and declarations:
- char represents printable characters and may be signed or unsigned depending on the platform; bool represents false and true. section 5.2
- Narrow integer types do not participate directly in arithmetic; before arithmetic, they are promoted to signed int. section 5.2
- An array’s base type may itself be an array, producing a multidimensional array; read nested declarations from the inside out. section 6.1.1
- Every pointer type is derived from a base type, and pointers with distinct base types are distinct types. section 12.0
Table 5.1. Base types according to the four main type classes. Types with a gray background don’t allow for arithmetic; they are promoted before doing arithmetic. Type char is special since it can be unsigned or signed, depending on the platform. All types in this table are considered to be distinct types, even if they have the same class and precision. (view table figure)
| Class |
Systematic name |
Other name |
Rank |
|
|---|---|---|---|---|
| Integers | Unsigned | _Bool | bool | 0 |
| unsigned char | 1 | |||
| unsigned short | 2 | |||
| unsigned int | unsigned | 3 | ||
| unsigned long | 4 | |||
| unsigned long long | 5 | |||
| [Un]signed | char | 1 | ||
| signed char | 1 | |||
| signed short | short | 2 | ||
| Signed | signed int | signed or int | 3 | |
| signed long | long | 4 | ||
| signed long long | long long | 5 | ||
| Floating point | Real | float | ||
| double | ||||
| long double | ||||
| Complex | float _Complex | float complex | ||
| double _Complex | double complex | |||
| long double _Complex | long double complex | |||
Compare the four main classes of C base types, their alternate spellings, ranks, and the types promoted before arithmetic. section 5.2
