entry: numerical data types in C

zk/Numerical_data_types_in_C.md

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+---
+tags:
+  - C
+---
+
+# Numerical data types in C
+
+## Summary
+
+| Data type       | Memory  | Examples       |
+| --------------- | ------- | -------------- |
+| `int`           | 4 bytes | `0`, `-3`, `9` |
+| `short int`     | 2 bytes | `0`, `-3`, `9` |
+| `long int`      | 4 bytes | `0`, `-3`, `9` |
+| `long long int` | 8 bytes | `0`, `-3`, `9` |
+| `float`         | 4 bytes | `2.1882`       |
+| `double`        | 8 bytes | `2.18829801`   |
+
+## `int`
+
+An `int` can hold a signed or unsigned value or 0 but it cannot hold a decimal
+value.
+
+On most modern systems, an `int` typically allocates 4 bytes (32 bits) of
+memory. This is not always the case however and some systems may allocate only 2
+bytes.
+
+$2^32 = 4294967296$ thus for signed ints this provides a range -2,147,483,648 to
+2,147,483,647. For unsigned ints this provides a range 0 to 4,294,967,295.
+
+## `short int`
+
+The same properties of `int` but a smaller bit allocation - 2 bytes (16bits).
+
+$2^16 = 65536$ thus for signed short ints this provides a range -32,768 to
+32,767. For unsigned short ints this provides a range 0 - 65, 536.
+
+## `long int`
+
+Basically the same as `int` but you are guarenteed 4 bytes, independent of
+system.
+
+## `long long int`
+
+An extra-long `int` allocated 8 bytes (64bits).
+
+## `float`
+
+Use to hold decimal values. Allocated 4 bytes (32 bits) of memory. Holds less
+precision than a `double` but uses less memory.
+
+## `double`
+
+Use to hold decimal values. Allocated 8 bytes (32 bits) of memory. Provides
+greater precision than a `float` but uses more memory.