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Annotation of 43BSD/contrib/spms/src/bin/pfind/binary.c, revision 1.1

1.1     ! root        1: /* $Header$ */
        !             2: 
        !             3: /*
        !             4:  * Author: Peter J. Nicklin
        !             5:  */
        !             6: #include "yesno.h"
        !             7: 
        !             8: static char **STRINGS;                 /* pointer array containing strings */
        !             9: static int NSTRINGS;                   /* number of strings in STRINGS */
        !            10: 
        !            11: /*
        !            12:  * bininit() initializes and sorts the STRINGS pointer array.
        !            13:  */
        !            14: void
        !            15: bininit(argc, argv)
        !            16:        int argc;
        !            17:        char **argv;
        !            18: {
        !            19:        int qsort();                    /* quicker sort */
        !            20:        int strpcmp();                  /* pointed-to string comparison */
        !            21: 
        !            22:        NSTRINGS = argc;
        !            23:        STRINGS = argv;
        !            24:        qsort((char *) STRINGS, NSTRINGS, sizeof(char *), strpcmp);
        !            25: }
        !            26: 
        !            27: 
        !            28: 
        !            29: /*
        !            30:  * binsearch() returns integer YES if string is found in sorted pointer
        !            31:  * array STRINGS, otherwise NO. Uses binary search.
        !            32:  */
        !            33: binsearch(string)
        !            34:        char *string;                   /* string to be matched */
        !            35: {
        !            36:        int comp;                       /* compare string values */
        !            37:        int high;                       /* upper limit of array */
        !            38:        int low;                        /* lower limit of array */
        !            39:        int mid;                        /* middle of search range */
        !            40:        int strcmp();                   /* string comparison */
        !            41: 
        !            42:        low = 0;
        !            43:        high = NSTRINGS - 1;
        !            44:        while (low <= high)
        !            45:                {
        !            46:                mid = (low+high) / 2;
        !            47:                if ((comp = strcmp(string, STRINGS[mid])) < 0)
        !            48:                        high = mid - 1;
        !            49:                else if (comp > 0)
        !            50:                        low = mid + 1;
        !            51:                else
        !            52:                        return(YES);
        !            53:                }
        !            54:        return(NO);
        !            55: }
        !            56: 
        !            57: 
        !            58: 
        !            59: /*
        !            60:  * strpcmp() compares strings in a pointer array. Returns whatever strcmp()
        !            61:  * returns.
        !            62:  */
        !            63: static int
        !            64: strpcmp(s1, s2)
        !            65:        char **s1;
        !            66:        char **s2;
        !            67: {
        !            68:        int strcmp();                   /* string comparison */
        !            69: 
        !            70:        return(strcmp(*s1, *s2));
        !            71: }

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