实验4

task1.c
#include<stdio.h>
 #define N 4
 int main()
 {
     int a[N]={2,0,2,2};
     char b[N]={'2','0','2','2'};
     int i;
     printf("sizeof(int)=%d\n",sizeof(int));
     printf("sizeof(char)=%d\n",sizeof(char));
     printf("\n");
     for(i=0;i<N;++i)
     {
         printf("%p:%d\n",&a[i],a[i]);
    }
    printf("\n");
    for(i=0;i<N;++i)
    {
         printf("%p:%c\n",&b[i],b[i]);
    }
    printf("\n");
    printf("a=%p\n",a);
    printf("b=%p\n",b);
    return 0;
 }

task1.2.c
#include<stdio.h>
#define N 2
#define M 3
int main()
{
    int a[N][M]={{1,2,3},{4,5,6}};
    char b[N][M]={{'1','2','3'},{'4','5','6'}};
    int i,j;
    for(i=0;i<N;++i)
    {
        for(j=0;j<M;++j)
        {
            printf("%p:%d\n",&a[i][j],a[i][j]);
        }
    }
    printf("\n");
    for(i=0;i<N;++i)
    {
        for(j=0,j<M;++j)
        {
            printf("%p:%c\n",&b[i][j],b[i][j]);
        }
    }
    return 0;
}

task2.c
#include<stdio.h>
#define N 13
int days_of_year(int year,int month,int day);
int main()
{
    int year,month,day;
    int days;
    while(scanf("%d%d%d",&year,&month,&day)!=EOF)
    {
        days=days_of_year(year,month,day);
        printf("%4d-%02d-%02d是这一年的第%d天.\n\n",year,month,day,days);
    }
    return 0;
}
int days_of_year(int year,int month,int day)
{
    int a[N],i,m=0,days;
    for(i=1;i<8;++i)
    {
        if(i==2)
        {
            if(year%4==0,year%100==0||year%400==0)
            {
                a[i]=29;
            }
            else
                a[i]=28;
        }
        else if(i%2==0)
        {
            a[i]=30;
        }
        else
        {
            a[i]=31;
        }
    }
    for(i=8;i<13;++i)
    {
        if(i%2==0)
        {
            a[i]=31;
        }
        else
        {
            a[i]=30;
        }
    }
    for(i=1;i<=month;++i)
    {
        if(i==1)
        {
            m=0;
        }
        else
            m=m+a[i];
    }
    days=m+day;
    return days;
}

task3.c
#include<stdio.h>
#define N 5
void input(int x[],int n);
void output(int x[],int n);
double average(int x[],int n);
void sort(int x[],int n);
int main()
{
    int scores[N];
    double ave;
    printf("录入%d个分数:\n",N);
    input(scores,N);
    printf("\n输出课程分数:\n");
    output(scores,N);
    printf("\n课程分数处理:计算均分、排序...\n");
    ave=average(scores,N);
    sort(scores,N);
    printf("\n输出课程均分:%.2f\n",ave);
    printf("\n输出课程分数（高->低）:\n");
    output(scores,N);
    return 0;
}
void input(int x[],int n)
{
    int i;
    for(i=0;i<n;++i)
    {
        scanf("%d",&x[i]);
    }
}
void output(int x[],int n)
{
    int i;
    for(i=0;i<n;++i)
    {
        printf("%d ",x[i]);
    }
    printf("\n");
}
double average(int x[],int n)
{
    int i,j=0;
    double ave;
    for(i=0;i<n;++i)
    {
        j=j+x[i];
    }
    ave=j/n;
    return ave;
}
void sort(int x[],int n)
{
    int i,j,t;
    for(i=0;i<n-1;++i)
    {
        for(j=0;j<n-i-1;++j)
        {
            if(x[j]<x[j+1])
            {
                t=x[j];
                x[j]=x[j+1];
                x[j+1]=t;
            }
        }
    }
}

task4.c
#include<stdio.h>
void dec2n(int x,int n);
int main()
{
    int x;
    printf("输入一个十进制整数:");
    scanf("%d",&x);
    dec2n(x,2);
    dec2n(x,8);
    dec2n(x,16);
    return 0;
}
void dec2n(int x,int n)
{
    int  m,i, a[100];
    while(x!=0)
    {
        m=x%n;
        a[i]=m;
        x/=n;
        i++;
    }
    for(int j=i-1;j>=0;j--)
    {
        if(a[j>9])
        {
            printf("%c",a[j]-10+'A');
        }
        else 
        {
            printf("%d",a[j]);
        }
    }
    printf("\n");
}

task5.c
#include<stdio.h>
int main()
{
    int n,i,j,k;
    printf("Enter n:");
    while(scanf("%d",&n)!=EOF)
    {
        for(i=1;i<=n;++i)
        {
            for(j=1;j<=n;++j)
            {
                k=i>j?j:i;
                printf("%3d",k);
            }
            printf("\n");
        }
        printf("Enter n:");
    }
    return 0;
}

task5.c
#include<stdio.h>
#define N 80
int main()
{
    int i;
    char t;
    char views1[N]="hey,c,i hate u.";
    char views2[N]="hey,c,i love u.";
    printf("original views:\n");
    printf("views1:");
    puts(views1);
    printf("views2:");
    puts(views2);
    printf("\nswapping...\n\n");
    for(i=0;views1[i]!='\0';++i)
    {
        t=views1[i];
        views1[i]=views2[i];
        views2[i]=t;
    }
    printf("views1:");
    puts(views1);
    printf("views2:");
    puts(views2);
    return 0;
}

task7.c
#include<stdio.h>
#include<string.h>
#define N 5
#define M 20
void bubble_sort(char str[][M],int n);
int main()
{
    char name[][M]={"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]);
    } 
    printf("\n排序中...\n");
    bubble_sort(name,N);
    printf("\n按字典序输出名单:\n");
    for(i=0;i<N;i++) 
    {
        printf("%s\n",name[i]);
    }
    return 0;
}
void bubble_sort(char str[][M],int n)
{
    char a[M];
    int i,j;
    for(i=0;i<N;++i)
    {
        for(j=0;j<N-1;++j)
        {
            if(strcmp(str[j],str[j+1])>0)
            {
                strcpy(a,str[j]);
                strcpy(str[j],str[j+1]);
                strcpy(str[j+1],a);
            }
          
        }
    }
}