Free
free is a C standard-library function that releases dynamically allocated storage previously obtained from a compatible allocation function.
Modern C, Third Edition
free is a C library function that releases dynamically allocated storage previously obtained from a compatible allocation function.
- How it is used
- Manages the lifetime of dynamically allocated storage and closes allocation paths during normal and error cleanup.
- How deep it goes
- Defines valid pointer origins, pairing rules, leaks, realloc interactions, and cleanup control flow, but does not descend into allocator internals.
- Examples
- Uses an allocated double array, a printing buffer, realloc failure, I/O failure, and a shared goto cleanup path.
- What you can do after
- Apply ownership accounting and cleanup paths that release allocated storage without leaks or invalid frees.
Modern C
free is a C standard library function that releases dynamically allocated storage previously obtained from an allocation function.
- How it is used
- Manages storage lifetimes for varying collections, user input, web queries, graphs, matrices, and audio streams.
- How deep it goes
- Defines release and pointer-validity rules, but does not descend into allocator implementation.
- Examples
- Uses a large vector of doubles and allocation/free counting to illustrate dynamic storage and lifecycle consistency.
- What you can do after
- Operate dynamic storage safely by releasing valid allocations and identifying leaks or invalid free attempts.
Related concepts
- mallocused by · malloc is a C standard-library function that allocates a specified number of uninitialized bytes and returns a pointer to the storage or a null pointer on failure.
- destructorcontrasts with · A destructor is an operation associated with an object or value that performs cleanup when its lifetime ends.
- custom allocatorused by · A custom allocator is a programmer- or library-supplied component that manages dynamically allocated storage according to specified requirements or policies.
- realloccontrasts with · realloc is a C standard-library function that changes the size of an allocated memory block while preserving its existing contents up to the applicable size.
- callocuses · calloc is a C standard-library function that allocates contiguous storage for an array of elements and initializes all allocated bytes to zero.
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