How can I define a datatype with 1 bit size in C?

I want to define a datatype for boolean true/false value in C. Is there any way to define a datatype with 1 bit size to declare for boolean?

Solution

Maybe you are looking for a bit-field:

struct bitfield
{
     unsigned b0:1;
     unsigned b1:1;
     unsigned b2:1;
     unsigned b3:1;
     unsigned b4:1;
     unsigned b5:1;
     unsigned b6:1;
     unsigned b7:1;
};

There are so many implementation-defined features to bit-fields that it is almost unbelievable, but each of the elements of the struct bitfield occupies a single bit. However, the size of the structure may be 4 bytes even though you only use 8 bits (1 byte) of it for the 8 bit-fields.

There is no other way to create a single bit of storage. Otherwise, C provides bytes as the smallest addressable unit, and a byte must have at least 8 bits (historically, there were machines with 9-bit or 10-bit bytes, but most machines these days provide 8-bit bytes only — unless perhaps you're on a DSP where the smallest addressable unit may be a 16-bit quantity).