Void pointer
A void pointer is a C pointer of type void* that can hold the address of an object without specifying its pointed-to object type.
Modern C, Third Edition
A void pointer is a C pointer to void that can hold the address of an object of any object type, subject to valid conversions and qualification rules.
- How it is used
- Supports generic data interfaces such as qsort and bsearch while leaving type recovery and safety to the caller.
- How deep it goes
- Explains conversions, identity preservation, qualification, and generic-interface hazards, but stops short of detailed implementation internals.
- Examples
- Uses qsort and bsearch signatures, an unsigned comparator, and invalid integer subtraction to expose generic-interface constraints.
- What you can do after
- Apply it via qsort or bsearch while matching element types, qualifications, sizes, and comparator behavior.
Modern C
A void pointer is a C pointer value of type void* that can hold the address of an object without retaining its pointed-to type information.
- How it is used
- Uses void* to abstract object types and make dynamic-allocation interfaces applicable to many object types.
- How deep it goes
- Defines conversion guarantees, storage abstraction, allocation behavior, and avoidance guidance, but does not develop implementation internals.
- Examples
- Demonstrates a double vector allocated with malloc and sized using sizeof *largeVec.
- What you can do after
- Apply void* through malloc and free while preserving correct object-pointer conversions and allocation sizes.
Related concepts
- referenceequivalent to · A reference is an indirect value or relationship that identifies or provides access to another value, object, resource, or source.
- function pointer typecontrasts with · A function pointer is a value that designates a callable function and can be stored, passed, or invoked indirectly.
- type informationcontrasts with · Type information is information that identifies or describes the types associated with program values, expressions, functions, or other typed entities.
- format stringused by · A format string is a character sequence containing literal text and directives that specify how supplied values are represented in formatted input or output.
- comparison functionused by · A comparison function or strategy compares two values and indicates their relative ordering, and sometimes whether they are equivalent.
- type safetycontrasts with · Type safety is the property that program operations respect type constraints, preventing or detecting invalid uses of values.
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