This section describes the storage formats of the data types available in C51. C51 provides you with a number of basic data types to use in your C programs. The following table lists these data types along with size requirements and value ranges.
| Data Type |
Bits |
Bytes |
Value Range |
| bit |
1 |
0 to 1 |
|
| signed char |
8 |
1 |
-128 to +127 |
| unsigned char |
8 |
1 |
0 to 255 |
| enum |
16 |
2 |
-32768 to +32767 |
| signed short |
16 |
2 |
-32768 to +32767 |
| unsigned short |
16 |
2 |
0 to 65535 |
| signed int |
16 |
2 |
-32768 to +32767 |
| unsigned int |
16 |
2 |
0 to 65535 |
| signed long |
32 |
4 |
-2147483648 to 2147483647 |
| unsigned long |
32 |
4 |
0 to 4294967295 |
| float |
32 |
4 |
±1.175494E-38 to ±3.402823E+38 |
| data *, |
8 |
1 |
0x00 to 0xFF |
| code*, |
16 |
2 |
0x0000 to 0xFFFF |
| untyped ptr |
24 |
3 |
Memory type (1 byte) 1 to 5; Offset (2 bytes) 0x0000 to 0xFFFF |
Other data types, like structures and unions, may contain scalars from this table. All elements of these data types are allocated sequentially and are byte-aligned due to the 8-bit architecture of the 8051 family.