Type Sizes

In C, the "size" (in memory) of a type is not guaranteed to be the same on all systems. That's because the size of a type is dependent on the system's architecture. For example, on a 32-bit system, the size of an int is usually 4 bytes, while on a 64-bit system, the size of an int can sometimes be 8 bytes – of course, you never know until you run sizeof with the compiler you plan on using.

However, some types are always guaranteed to be the same. Here's a list of the basic C data types along with their typical sizes in bytes. Note that sizes can vary based on the platform (e.g., 32-bit vs. 64-bit systems):

Basic C Types and Sizes

• char
  • Size: 1 byte
  • Represents: Single character.
  • Notes: Always 1 byte, but can be signed or unsigned.
• float
  • Size: 4 bytes
  • Represents: Single-precision floating-point number.
• double
  • Size: 8 bytes
  • Represents: Double-precision floating-point number.

The actual sizes of these types can be determined using the sizeof operator in C for a specific platform, which we'll learn about next.