实验五

Part1

#include  <stdio.h>
const int N=5;
int binarySearch(int x[], int n, int item);
int main() {
int a[N]={2,4,17,23,45};
int i,index, key;    
printf("数组a中的数据:\n");
for(i=0;i<N;i++)
printf("%d ",a[i]);
printf("\n");
printf("输入待查找的数据项: ");
scanf("%d", &key);
index=binarySearch(a,N,key);
if(index>=0) 
printf("%d在数组中，下标为%d\n", key, index);
else
printf("%d不在数组中\n", key); 
return 0;}
int binarySearch(int x[], int n, int item) {
int low, high, mid;
low = 0;
high = n-1;
while(low <= high) {
mid = (low+high)/2;
if (item == x[mid])
return mid;
else if(item < x[mid])
high = mid - 1;
else
low = mid + 1;
}
return -1;
}

#include  <stdio.h>
const int N=5;
int binarySearch(int *x, int n, int item);
int main() {
int a[N]={2,6,13,21,30};
int i,index, key;
printf("数组a中的数据:\n");
for(i=0;i<N;i++)
printf("%d ",a[i]);
printf("\n");
printf("输入待查找的数据项: ");
scanf("%d", &key);
index=binarySearch(a,N,key);
if(index>=0) 
printf("%d在数组中，下标为%d\n", key, index);
else
printf("%d不在数组中\n", key); 
return 0;
}
int binarySearch(int *x, int n, int item) {
int low, high, mid;
low = 0;
high = n-1;
while(low <= high) {
mid = (low+high)/2;
if (item == *(x+mid))
return mid;
else if(item < *(x+mid))
high = mid - 1;
else
low = mid + 1;
}
return -1;
}

指针不改变数组顺序，占用内存小执行完成程序更快。

Part2选择法排序

#include <stdio.h>
#include <string.h>
void selectSort(char str[][20], int n );
int main() {
char name[][20] = {"John", "Alex", "Joseph", "Candy", "Geoge"};
int i;
printf("输出初始名单:\n");
for(i=0; i<5; i++)
printf("%s\n", name[i]);
selectSort(name, 5); 
printf("按字典序输出名单:\n");
for(i=0; i<5; i++)
printf("%s\n", name[i]);
return 0;
} 
void selectSort(char str[][20], int n) {
int i, j, k;
char temp[20];
for(i=0; i<n-1; i++) {
k = i;
for(j=i+1; j<n; j++)
if (strcmp(str[j],str[k])<0)
k = j;
if(k != i) {  
strcpy(temp,str[i]);
strcpy(str[i],str[k]);
strcpy(str[k],temp);
}
}
}

使用指针对字符串进行操作时注意\0的结束符 注意形参实参写法差异 数组元素表示方式

问题很多借鉴了同学的作业，需要加油。