() — Coherent 3.1.0


cast                        Definition                       cast




The cast  operation ``coerces'' a variable from  one data type to
another.

There are two  reasons to cast a variable.  The  first is to con-
vert a  variable's data into  a form acceptable to  a given func-
tion.  For example, the function hypot takes two doubles.  If the
variables leg_x and leg_y are floats, the rules of C require that
they be cast automatically to double.  If the compiler did not do
not do  this, hypot  would grab a  double's worth of  memory: the
four bytes of your float,  plus four bytes of whatever happens to
be sitting on the stack.  The leads to results that are less than
totally accurate.

The other reason to cast a  variable is when you cast one type of
pointer to another.  For example,


        char *foo;
        int *bar;
        bar = (int *)foo;


Although foo and  bar are of the same length,  you would cast foo
in this instance to stop  the C compiler from complaining about a
type mismatch.

***** See Also *****

data formats, data types, definitions



























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