/* * 1.二分查找也应用了递归的思想。 * 2.这里的代码只是demo */#include <stdio.h>#include "strlib.h"
int FindStringInSortedArray(string key, string array[], int n);
static int BinarySearch(string key, string array[], int low, int high);
/* * Function: FindStringInSortedArray * Usage: index = FindStringInSortedArray(key, array, n); * ------------------------------------------------------ * This function searches the array looking for the specified * key. The argument n specifies the effective size of the * array, which must be sorted according to the lexicographic * order imposed by StringCompare. If the key is found, the * function returns the index in the array at which that key * appears. (If the key appears more that once in the array, * any of the matching indices may be return). If the key * does not exist in the array, the function returns -1. In * this implementation, FindStringInSortedArray is simply a * wrapper; all the work is done by the recursive function * BinarySearch. */int FindStringInSortedArray(string key, string array[], int n) {    return BinarySearch(key, array, 0, n - 1);}
/* * Function: BinarySearch * Usage: index = BinarySearch(key, array, low, high); * --------------------------------------------------- * This function does the work for FindStringInSortedArray. * The only difference is that BinarySearch takes both the * upper and lower limit of the search. */static int BinarySearch(string key, string array[], int low, int high) {    int mid, cmp;
    if (low > high) {        return -1;    }    mid = (low + high) / 2;    cmp = StringCompare(key, array[mid]);    if (cmp == 0) {        return mid;    }    if (cmp < 0) {        return BinarySearch(key, array, low, mid - 1);    } else {        return BinarySearch(key, array, mid + 1, high);    }}
int main() {    int index;    char *arr[] = {"Programming Abstractions in C", "Hello World", "C"};    index = FindStringInSortedArray("C", arr, 3);    printf("index is: %d", index);    return 0;}