Programming in C

448 Appendix A C Language Summary

In each case, the type of the result is the type of the elements contained in a. See

Section 5.15 for a summary of operations with pointers and arrays.

5.14 Basic Operations with Structures^1

Given that

x is a modifiable lvalue expression of type struct s;

y is an expression of type struct s;

m is the name of one of the members of the structure s;

v is an expression;

then the expression

x references the entire structure and is of type struct s;

y.m references the member mof the structure yand is of the type declared

for the member m;

x.m = v assigns vto the member mof xand is of the type declared for the

member m;

x = y assigns yto xand is of type struct s;

f (y) calls the function f, passing contents of the structure yas the argu-

ment; inside f, the formal parameter must be declared to be of type

struct s;

return y; returns the structure y;the return type declared for the function must

be struct s.

5.15 Basic Operations with Pointers

Given that

x is anlvalueexpression of type t;

pt is a modifiable lvalue expression of type “pointer to t”;

v is an expression;

then the expression

&x produces a pointer to xand has type “pointer to t”;

pt = &x sets ptpointing to xand has type “pointer to t”;

pt = 0 assigns the null pointer to pt;

pt == 0 tests to see if ptis null;

*pt references the value pointed to by ptand has type t;

*pt = v stores the value of vinto the location pointed to by ptand has type t.

1. Also applies to unions.

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