The most common reason that a program needs to know how many bits are in
an integer type is for using an array of long int as a bit vector.
You can access the bit at index n with
vector[n / LONGBITS] & (1 << (n % LONGBITS))
provided you define LONGBITS as the number of bits in a
long int.
There is no operator in the C language that can give you the number of
bits in an integer data type. But you can compute it from the macro
CHAR_BIT, defined in the header file `limits.h'.
CHAR_BIT
char---eight, on most systems.
The value has type int.
You can compute the number of bits in any data type type like
this:
sizeof (type) * CHAR_BIT
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