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/*
find方法利用折半查找算法查找整数m在数组中的位置。若找到返回其下标值,反之返回-1
*/
#include <stdio.h>
#define M 5
int main() {
int find(int data[], int num);// 函数声明
int data[5] = {23, 45, 123, 222, 254};
int i = 0, result = 0;
int num = 0;
printf("The datas of data[5] are:\n");
for(i = 0; i < M; i++) {
printf("%d\t", data[i]);
}
printf("\nPlease input the num you want to find:\n");
scanf("%d", &num);
result = find(data, num);
if(result >= 0) {
printf("The index is %d\n", result);
} else {
printf("Not be find!!\n");
}
return 0;
}
// 折半查找算法
int find(int data[], int num) {
int low = 0, high = M-1, mid = 0;
while(low <= high) {
mid = (low + high) / 2;
if(num < data[mid]) {
high = mid - 1;
} else if(num > data[mid]) {
low = mid + 1;
} else {
return mid;
}
}
return -1;
}