Informix DataBlade API Programmer's Manual DataBlade API Function Descriptions

The mi_zalloc() function allocates and zero-fills a block of memory of the given size and returns a pointer to a block of memory of the specified size.

void *mi_zalloc (size)

mi_integer size;

size	is the number of bytes to allocate and fill with zeroes.

Valid in Client LIBMI Application?	Valid in User-Defined Routine?
Yes	Yes

The mi_zalloc() function allocates size number of bytes of user memory for a DataBlade API module. The mi_zalloc() function behaves exactly like mi_alloc() except that mi_zalloc() fills the allocated block of memory with zeroes before the function returns the pointer to the memory.

The mi_zalloc() function allocates the memory in the current memory duration. By default, the current default duration is PER_ROUTINE. In C UDRs, the database server also automatically frees memory allocated with mi_zalloc() when an exception is raised.

Important: Use DataBlade API memory-management functions, such as mi_zalloc(), to allocate memory in C UDRs. Use of a DataBlade API memory-management function guarantees that the database server automatically frees the memory, especially in the cases of return values or exceptions, where the UDR would not otherwise be able to free the memory.

In client LIBMI applications, mi_zalloc() works exactly as malloc() does: it allocates storage on the heap of the client process. However, the database server does not perform any automatic garbage collection. Therefore, the client LIBMI application must use mi_free to explicitly free all allocations that mi_zalloc() makes.

Important: Client LIBMI applications ignore memory duration.

Client LIBMI applications can use either DataBlade API memory-management functions or system memory-management functions (such as malloc()).

The mi_zalloc() function returns a pointer to the newly allocated memory. Cast this pointer to match the structure of the user-defined buffer or structure that you allocate. A DataBlade API module can use mi_free() to free memory allocated by mi_zalloc() when that memory is no longer needed.

The mi_zalloc() function does not throw an MI_Exception event when it encounters a runtime error. Therefore, it does not cause callbacks to be invoked.

See the descriptions of the following functions: mi_alloc(), mi_dalloc(), mi_free(), and mi_switch_mem_duration().

For more information on memory allocation and memory duration, see Managing User Memory.