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JudyL_funcs(3) Library Functions Manual JudyL_funcs(3)


JudyL - C library for creating and accessing a dynamic array of words, using any value of a word as an index


PPvoid_t JudyLIns(       PPvoid_t PPJLArray, Word_t    Index, PJError_t PJError);
int      JudyLDel(       PPvoid_t PPJLArray, Word_t    Index, PJError_t PJError);
PPvoid_t JudyLGet(       Pcvoid_t  PJLArray, Word_t    Index, PJError_t PJError);
Word_t   JudyLCount(     Pcvoid_t  PJLArray, Word_t    Index1, Word_t    Index2, PJError_t PJError);
PPvoid_t JudyLByCount(   Pcvoid_t  PJLArray, Word_t    Nth,  Word_t * PIndex,  PJError_t PJError);
Word_t   JudyLFreeArray( PPvoid_t PPJLArray, PJError_t PJError);
Word_t   JudyLMemUsed(   Pcvoid_t  PJLArray);
PPvoid_t JudyLFirst(     Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
PPvoid_t JudyLNext(      Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
PPvoid_t JudyLLast(      Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
PPvoid_t JudyLPrev(      Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
int      JudyLFirstEmpty(Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
int      JudyLNextEmpty( Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
int      JudyLLastEmpty( Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
int      JudyLPrevEmpty( Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);


A macro equivalent exists for each function call. Because the macro forms are sometimes faster and have a simpler error handling interface than the equivalent functions, they are the preferred way of calling the JudyL functions. See JudyL(3) for more information. The function call definitions are included here for completeness.

One of the difficulties in using the JudyL function calls lies in determining whether to pass a pointer or the address of a pointer. Since the functions that modify the JudyL array must also modify the pointer to the JudyL array, you must pass the address of the pointer rather than the pointer itself. This often leads to hard-to-debug programmatic errors. In practice, the macros allow the compiler to catch programming errors when pointers instead of addresses of pointers are passed.

The JudyL function calls have an additional parameter beyond those specified in the macro calls. This parameter is either a pointer to an error structure, or NULL (in which case the detailed error information is not returned).

In the following descriptions, the functions are described in terms of how the macros use them (only in the case of #define JUDYERROR_NOTEST 1). This is the suggested use of the macros after your program has been fully debugged. When the JUDYERROR_NOTEST macro is not specified, an error structure is declared to store error information returned from the JudyL functions when an error occurs.

Notice the placement of the & in the different functions.

#define JLI(PValue, PJLArray, Index)  \

PValue = JudyLIns(&PJLArray, Index, PJE0)

#define JLD(Rc_int, PJLArray, Index)  \

Rc_int = JudyLDel(&PJLArray, Index, PJE0)

#define JLG(PValue, PJLArray, Index)  \

PValue = JudyLGet(PJLArray, Index, PJE0)

#define JLC(Rc_word, PJLArray, Index1, Index2)  \

Rc_word = JudyLCount(PJLArray, Index1, Index2, PJE0)

#define JLBC(PValue, PJLArray, Nth, Index) \

PValue = JudyLByCount(PJLArray, Nth, &Index, PJE0)

#define JLFA(Rc_word, PJLArray) \

Rc_word = JudyLFreeArray(&PJLArray, PJE0)

#define JLMU(Rc_word, PJLArray) \

Rc_word = JudyLMemUsed(PJLArray)

#define JLF(PValue, PJLArray, Index) \

PValue = JudyLFirst(PJLArray, &Index, PJEO)

#define JLN(PValue, PJLArray, Index) \

PValue = JudyLNext(PJLArray, &Index, PJEO)

#define JLL(PValue, PJLArray, Index) \

PValue = JudyLLast(PJLArray, &Index, PJEO)

#define JLP(PValue, PJLArray, Index) \

PValue = JudyLPrev(PJLArray, &Index, PJEO)

#define JLFE(Rc_int, PJLArray, Index) \

Rc_int = JudyLFirstEmpty(PJLArray, &Index, PJEO)

#define JLNE(Rc_int, PJLArray, Index) \

Rc_int = JudyLNextEmpty(PJLArray, &Index, PJEO)

#define JLLE(Rc_int, PJLArray, Index) \

Rc_int = JudyLLastEmpty(PJLArray, &Index, PJEO)

#define JLPE(Rc_int, PJLArray, Index) \

Rc_int = JudyLPrevEmpty(PJLArray, &Index, PJEO)


Definitions for all the Judy functions, the types Pvoid_t, Pcvoid_t, PPvoid_t, Word_t, JError_t, and PJError_t, the constants NULL, JU_ERRNO_*, JERR, PPJERR, and PJE0, are provided in the Judy.h header file (/usr/include/Judy.h). Note: Callers should define JudyL arrays as type Pvoid_t, which can be passed by value to functions that take Pcvoid_t (constant Pvoid_t), and also by address to functions that take PPvoid_t.

The return type from most JudyL functions is PPvoid_t so that the values stored in the array can be pointers to other objects, which is a typical usage, or cast to a Word_t * when a pointer to a Value is required instead of a pointer to a pointer.


Judy was invented by Doug Baskins and implemented -Packard.


Judy(3), Judy1(3), JudyL(3), JudySL(3), JudyHS(3),
the Judy website,, for more information and Application Notes.