_MemCmp( ) API Library Routine

Visual FoxPro 9.0 SP2

_MemCmp( ) API Library Routine


int _MemCmp(void FAR ptr1, void FAR ptr2, unsigned int length) void FAR ptr1; / First point to start compare. / void FAR ptr2; /* Second point to start compare. / unsigned int length; / How much to compare in bytes. */

Remarks

_MemCmp( ) compares each byte in the two areas, starting with the leftmost byte in each, until two bytes don't match. _MemCmp( ) returns 0 if all bytes in the areas match, a positive number if the first unmatched byte in the first area is greater than the corresponding byte in the second area, or a negative number if the first unmatched byte in the second area is greater than the corresponding byte in the first area.

For more information on how to create an API library and integrate it with Visual FoxPro, see Accessing the Visual FoxPro API.

Example

The following example uses _MemCmp( ) to compare two character parameters up to the length of the first unmatched byte.

Visual FoxPro Code

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SET LIBRARY TO MEMCMP ? MEMCMP("Hello, world.", "Hello, world.") && returns 0 ? MEMCMP("Hello, world.", "Hello, wurld.") && returns non-0

C Code

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#include <pro_ext.h> #define min(a, b) ((a) < (b) ? (a) : (b)) FAR Example(ParamBlk FAR parm) { int LenToCmp, RetValue; LenToCmp = min(parm->p[0].val.ev_length, parm->p[1].val.ev_length); _HLock(parm->p[0].val.ev_handle); _HLock(parm->p[1].val.ev_handle); RetValue = _MemCmp(_HandToPtr(parm->p[0].val.ev_handle), _HandToPtr(parm->p[1].val.ev_handle), LenToCmp); _RetInt(RetValue, 10); // does return control here _HUnLock(parm->p[0].val.ev_handle); _HUnLock(parm->p[1].val.ev_handle); } FoxInfo myFoxInfo[] = { {"MEMCMP", (FPFI) Example, 2, "C,C"}, }; FoxTable _FoxTable = { (FoxTable FAR ) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo };

Copy Code

#include <pro_ext.h>
#define min(a, b) ((a) < (b) ? (a) : (b))
FAR Example(ParamBlk FAR *parm)
{
   int LenToCmp, RetValue;
   LenToCmp = min(parm->p[0].val.ev_length, parm->p[1].val.ev_length);
   _HLock(parm->p[0].val.ev_handle);
   _HLock(parm->p[1].val.ev_handle);
   RetValue = _MemCmp(_HandToPtr(parm->p[0].val.ev_handle),
      _HandToPtr(parm->p[1].val.ev_handle), LenToCmp);
   _RetInt(RetValue, 10); // does return control here
   _HUnLock(parm->p[0].val.ev_handle);
   _HUnLock(parm->p[1].val.ev_handle);
}
FoxInfo myFoxInfo[] = {
   {"MEMCMP", (FPFI) Example, 2, "C,C"},
};
FoxTable _FoxTable = {
   (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};

_MemCmp( ) API Library Routine

Remarks

Example

Visual FoxPro Code

C Code

See Also

Reference

Concepts

Other Resources