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Arrow operator

As explained in Modern C

The arrow operator is the C operator that accesses a structure or union member through a pointer to that aggregate.

double timespec_diff(struct timespec const* later, struct timespec const* sooner) { return later->tv_sec - sooner->tv_sec; } Here, -> accesses a structure member through a pointer. It is equivalent to (*later).tv_sec, including the required parentheses. section 11.2

Accessing pointed-to members

The expression later->tv_sec is not itself a pointer; it produces the member object, whose type is long. The complete timespec_diff example also uses -> for tv_nsec and handles reversed times. section 11.2

TAKEAWAY

  • Use pointer->member when the left operand points to a structure or union; use object.member when it does not. section 11.2
  • Pointer-based rational-number functions use -> to modify members and may first test whether the pointer is null. section 11.2

How Modern C covers it

How deep it goes
Defines syntax, equivalence with (*pointer).member, result type, and practical examples without descending into pointer internals.
Examples
Uses timespec_diff and rational-number functions including rat_destroy, rat_normalize, rat_extend, and rat_sumup.
What it assumes
Assumes familiarity with pointers, structures, member access, and pointer parameters.
What you can do after
Apply it in C to read or modify structure and union members through pointers.
How it connects
Connects pointers with structures, unions, member access, null-pointer checks, and rational-number operations.
Cover of Modern C
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Modern C. The section links point to the parts of the book it draws on.