Zvals

In this chapter the “zval” data structure, which is used to represent PHP values, is introduced. We explain the concepts behind zvals and how to use them in extension code.

Contents:

• Basic structure
  • Types and values
  • Access macros
  • Setting the value
• Memory management
  • Value- and reference-semantics
  • Reference-counting and copy-on-write
  • Allocating and initializing zvals
  • Managing the refcount and zval destruction
  • Copying zvals
  • Separating zvals
• Casts and operations
  • Basic operations
  • Comparisons
  • Casts