task5

1.

#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");
}

 

 

交换3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;     

    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");
}

 

 交换3次

2.

#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,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;
}

 

 

 

 

 

 

 3.

#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)
{
    char temp[5][20];
    int i,j,d;
    for (i = 0; i < n - 1; i++)
    {
       
        for (j = i + 1; j < n; j++)
        {
            if (strcmp(str[i], str[j])> 0)
            {
                strcpy(temp[0], str[i]);
                strcpy(str[i],str[j]);
                strcpy(str[j],temp[0]);

            }
        }
    }

}

 

 4.

#include <stdio.h>

int main()
{
    int n;
    int *pn;

    n = 42;
    pn = &n;

    printf("%#x: %d\n", &n, n);
    printf("%#x: %#x\n", &pn, pn);
    printf("%d\n", *pn);

    return 0;
}

 

 （1）.0x56f818

(2).0x56f80c,n的地址

（3）.n存储的数

5.

#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）.可以

（2）.可以

Q:字符数组的交换只能通过函数实现？