# 实验五

#include <stdio.h>
#define N 5
void output(int x[], int n);
int main()
{
int x[N] = {9, 55, 30, 27, 22};
int i;
int k;
int t;
printf("original array:\n");
output(x, N);
k = 0;
for(i=1; i<N; ++i)
if(x[i] > x[k])
k = i;
if(k != N-1)
{
t = x[N-1];
x[N-1] = x[k];
x[k] = t;
}
printf("after swapped:\n");
output(x, N);
return 0;
}
void output(int x[], int n)
{
int i;
for(i=0; i<n; ++i)
printf("%d ", x[i]);
printf("\n");
}


#include <stdio.h>
#define N 5
void output(int x[], int n);
int main()
{
int x[N] = {9, 55, 30, 27, 22};
int i;
int t;
printf("original array:\n");
output(x, N);
for(i=0; i<N-1; ++i)
if(x[i] > x[i+1])
{
t = x[i];
x[i] = x[i+1];
x[i+1] = t;
}
printf("after swapped:\n");
output(x, N);
return 0;
}
void output(int x[], int n)
{
int i;
for(i=0; i<n; ++i)
printf("%d ", x[i]);
printf("\n");
}


#include <stdio.h>
#define N 5
int binarySearch(int x[], int n, int item);
int main()
{
int a[N] = {2, 7, 19, 45, 66};
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,5,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 (x[mid]==item)
return mid;
else if (x[mid]>item)
high = mid - 1;
else
low = mid + 1;
}
return -1;
}


#include <stdio.h>
#define N 5
void selectSort(int a[], int n);
void input(int a[], int n);
void output(int a[], int n);
int main()
{
int a[N];
printf("输入%d个整数\n", N);
input(a, N);
printf("排序前的数据:\n");
output(a, N);
selectSort(a, N); // 调用selectSort()对数组a中的N个元素排序
printf("排序后的数据:\n");
output(a, N);
return 0;
}
void input(int a[], int n)
{
int i;
for (i = 0; i < n; i++)
scanf("%d", &a[i]);
}
void output(int a[], int n)
{
int i;
for (i = 0; i < n; i++)
printf("%d ", a[i]);
printf("\n");
}
void selectSort(int a[], int n)
{
int i, j, k, temp;
for (i = 0; i < n - 1; i++)
{
k = i; // k用于记录当前最小元素的下标
for (j = i + 1; j < n; j++)
if (a[j] < a[k])
k = j; // 如果a[j]比当前最小元素还要小，就更新k，确保它总是存放最小元素的下标
if (k != i)// 找到最小元素后，交换a[i]和a[k]
{
temp = a[i];
a[i] = a[k];
a[k] = temp;
}
}
}


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


#include <stdio.h>
int main()
{
int n;
int *pn;
n = 42;
pn = &n;
printf("&n = %#x, n = %d\n", &n, n);
printf("&pn = %#x, pn = %#x\n", &pn, pn);
printf("*pn = %d\n", *pn);
return 0;
}


① 整型变量n的地址是0x62fe1c；变量n里存放的数是42.

② 指针变量pn的地址是0x62fe10；变量pn里存放的是n的地址0x62fe1c.

③ 通过 *pn 间接访问的是n中存放的数字42.

#include <stdio.h>
#define N 5
int main()
{
int a[N] = {1, 9, 2, 0, 7};
int i;
int *p;
for(i=0; i<N; ++i)
printf("&a[%d] = %#x, a[%d] = %d\n", i, &a[i], i, a[i]);
printf("\n");
for(i=0; i<N; ++i)
printf("a+%d = %#x, *(a+%d) = %d\n", i, a+i, i, *(a+i));
printf("\n");
p = a;
for(i=0; i<N; ++i)
printf("p+%d = %#x, *(p+%d) = %d\n", i, p+i, i, *(p+i));
return 0;
}


① 通过 a[i] 和 *(p+i) 都可以访问到数组元素a[i].

② 通过 &a[i] 和 p+i 都可以获得元素a[i]的地址.

posted on 2021-12-13 16:54  黄爽  阅读(13)  评论(1编辑  收藏  举报