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;
    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");
}

//数组元素值交换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;
    
    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");
}

//数组元素值交换3次

// task1_1思路为从数组第一个元素开始，与下面元素依次比较，如果被比较元素大于初始元素则用较大元素继续与后续元素依次比较直至得出最大数并将其与最后一个元素进行交换
// task1_2思路为从数组第一个元素开始，与下面元素进行比较如果比被比较元素大，则两个元素进行一次交换，直至最大元素位于数组在最后一个元素上为止。 

 

#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(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);
    
    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;
         
         for(j = i + 1;j < n;j++)
             if(a[j] < a[k])
                 k = j;
                 
         if(k != i)
         {
             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 i, j, k;
    char a[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(a, str[k]);
            strcpy(str[k], str[i]);
            strcpy(str[i], a);
        }
    }
}

 

#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;
}

//n的地址是0x62fe1c,n里存放的数是42
//pn的地址是0x62fe10，pn里存放的是整型变量n的地址
//间接访问的是变量n里存放的数 

#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，一个为直接访问，一个为间接访问
 //2 可以。