实验5

#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; // 用于记录最大元素的下标
    int t; // 用作交换两个数组元素的中间变量
    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");
}

 

 1次

#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; // 用作交换两个数组元素的中间变量
    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");
}

 

 3次

第一种是从数组元素中选出最大并于最后元素调换

第二种是两两比较大的后移

#include <stdio.h>
#define N 5
int binarySearch(int x[], int n, int item); // 函数声明
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_s("%d", &key);
    index = binarySearch(a, N, key);
    // 调用函数binarySearch()在数组a中查找指定数据项key,并返回查找结果给index
    // 补足代码①
    // ×××
    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;
}
//函数功能描述：
//使用二分查找算法在数组x中查找特定值item，数组x大小为n
// 如果找到，返回其下标
// 如果没找到，返回-1
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>
#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_s(temp, str[k]);
            strcpy_s(str[k], str[i]);
            strcpy_s(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;
}

 

 

#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;
}