# NAG CL Interfaceh02xzc (nag_ip_free)

## 1Purpose

h02xzc is the function for freeing memory allocated by a NAG Library function to the h02 options structure, type Nag_H02_Opt. The function will only free memory which has been allocated to pointers within the options structure by an integer programming function; it will not free memory allocated by you. The standard C function free() must not be used for freeing NAG allocated memory in the H Chapter Introduction.

## 2Specification

 #include
 void h02xzc (Nag_H02_Opt *options, const char *p_name, NagError *fail)
The function may be called by the names: h02xzc or nag_ip_free.

## 3Description

The integer programming (IP) functions of the H Chapter Introduction have a number of optional parameters, which are set by means of a structure of type Nag_H02_Opt. Optional parameter values can be assigned to members of the options structure directly in the program text and/or by supplying the optional values in a file to be read by the function h02xyc.
The IP functions use pointers within the options structure as arrays. The appropriate amount of memory for the arrays will be allocated internally by the IP function being used. The same options structure may be used in several calls to an IP function: NAG allocated memory will be automatically freed and reallocated on each call to the IP function. This is the recommended method of use of the pointers within the options structure.
If users wish to free NAG allocated memory from the options structure at any point in their program, then h02xzc must be used to perform the freeing operation.
In most cases, memory may be allocated to the pointers in the options structure if the NAG default memory allocation is not wanted — h02xzc will not free this user allocated memory. Dynamic memory allocated by you should be freed by the standard C library function free(). If it is intended to re-enter a NAG IP function after this use of free(), with the intention of using the NAG default memory allocation, then the pointer involved must be set to NULL before re-entry.
The purpose of using h02xzc to free NAG allocated memory instead of free() is to allow the IP functions to maintain knowledge of which pointers have been allocated memory by a NAG function and which have been allocated by you. If h02xzc is not used to free the NAG allocated memory and the standard C function free() is used instead then there is the danger that any memory which is dynamically allocated will be freed by the IP function.
To conserve memory h02xzc should also be used to free NAG allocated memory within the options structure when that memory is no longer required, e.g., before returning from the function which calls the NAG Library h02 functions. Any memory not freed will, of course, be freed when your program terminates.

None.

## 5Arguments

1: $\mathbf{options}$Nag_H02_Opt * Input/Output
On entry: the options structure that was used in a call to an IP function in the H Chapter Introduction. The pointers within the structure may have either NAG allocated memory or user allocated memory.
On exit: those pointers selected (see argument p_name) which pointed to NAG allocated memory will have been freed and set to NULL. Any user allocated memory will not be freed.
2: $\mathbf{p_name}$const char * Input
On entry: a character string specifying which pointer is to be freed. The string should give the optional parameter or structure member name. If you wish to free all NAG allocated memory then an empty string "" or the string "all" should be given. Please note that p_name is case sensitive and as such upper-case letters should not be used unless explicitly required.
3: $\mathbf{fail}$NagError * Input/Output
The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

## 6Error Indicators and Warnings

NE_STR_UNKNOWN
String supplied, $〈\mathit{string}〉$, does not match name of any pointer in the options structure.

Not applicable.

## 8Parallelism and Performance

h02xzc is not threaded in any implementation.