C语言练习题【2】

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#define N 20
int main()
{
//调试下列程序，使之具有如下功能：输入10个整数，按每行3个数输出这些整数，最后输出10个整数的平均值。写出调试过程。
#if(0)
    int a[N] ,i , sum = 0;
    printf("input 10 integer\n");
    for ( i = 0; i < N; i++)
    {
        scanf("%d",&a[i]);
    }
    for ( i = 0; i < N; i++)
    {
        sum += a[i];
        if(i % 3 == 0) printf("\n");
        printf("%3d",a[i]);
    }
    printf("\n");
    printf("\n");
    printf("10 integer average is %f",sum / 10.0);
#endif
//有一个3行4列的距阵，现要求编程求出其中最大的那个元素的值，以及它所在的行号与列号。下面程序的初始说明和输出语句如下所示，请补充完成该程序。
#if(0)
 int i , j ,row ,colum ,max;
 static int a[3][4] = {{1,2,3,4},{9,8,7,6},{-10,10,-5,2}};

 max = a[0][0] ;

 for ( i = 0; i < 3; i++)
 {
     for ( j = 0; j < 4; j++)
     {
         if(a[i][j] > max) {max = a[i][j] ,row = i , colum = j };
     }
 }




 printf("Max = %d, Row = %d , Colum = %d \n",max,row+1,colum+1);
#endif
 //数组中已存互不相同的10个整数，从键盘输入一个整数，输出与该值相同的数组元素下标。
#if(0)
 int i,x,a[10]={1,2,3,4,5,6,7,8,9,10};
 printf("input search num：");
 scanf("%d",&x);
 for ( i = 0; i < 10; i++)
 {
     if(a[i] == x) break;
 }
 if(i < 10) printf("该元素的下标为%d\n",i); 
 else printf("该数组没有%d\n",x);
#endif

#if(0)
int i, k, x,a[5]={1,3,5,7} ;
 scanf("%d",&x);
for ( k=4; k>0; k-- )     /* 从后向前比较 */
    if ( a[k-1] > x )
         a[k] = a[k-1]; /* 将大数向后移动 */
    else   break;         /* 找到插入的位置，退出 */
    a[k] = x;             /* 完成插入操作 */
    for (i=0; i<5; i++)     
        printf("%4d", a[i]);
    return 0;
#endif //有一个已排好序的数组，今有一个数，要求按原来排序的规律将它插入数组（从小到大排列）中。

//任意输入10个任意输入10个整数的数列，先将整数按照从大到小的顺序进行排序，然后输入一个整数插入到数列中，使数列保持从大到小的顺序
#if(0)
    int i ,j ,x ,temp , a[11];
    printf("输入十个整数：\n");
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",&a[i]);
    }
    for ( i = 0; i < 9; i++)
    {
        for ( j = 0; j < 9 - i; j++)
        {
            if(a[j]<a[j+1])
            {
                temp = a[j];
                a[j] = a[j+1];
                a[j+1] = temp;
            }
        }
    }
    printf("输入要插入的整数：\n");
    scanf("%d",&x);
    for ( i = 9; i >= 0 ; i--)
    {
        if( a[i] < x )
        {
          a[i+1] = a[i];
        }else break;
        a[i] = x;
    }
    for ( i = 0; i < 11; i++)
    {
        printf("%3d",a[i]);
    }
#endif

//输入十个互不相同的整数并存在数组中，找出最大元素，并删除
#if(0)
    int a[10] , i , j  , max;
    printf("请输入十个互不相同的整数\n");
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",&a[i]);
    }

    max = a[0];
    for ( i = 1; i < 10; i++)
    {
        if(a[i]>max) {max = a[i] ,j = i; }
    }
    for ( i = j; i < 10; i++)
    {
        a[i] = a[i+1];
    }
    for ( i = 0; i < 9; i++)
    {
        printf("%3d",a[i]);
    }
#endif

//从键盘上输入若干个学生的成绩，统计计算出平均成绩，并输出低于平均分的学生成绩，用输入负数结束输入
#if(0)
float x[1000] , sum = 0.0 , ave ,a;
int n = 0 , i;
printf("Enter mark ：\n");
scanf("%f",&a);
while (a>=0.0 && n<1000)
{
    sum += a;
    x[n] = a;
    n++;
    scanf("%f",&a);
}
ave = sum / n;

printf("Output：\n");
printf("ave = %f\n",ave);
for ( i = 0; i < n; i++)
{
    if(x[i]<ave) printf("%f\n",x[i]);
}
#endif

//打印如下杨辉三角形
#if(0)
//int a[6][6] , i , j;
//for ( i = 0; i < 6; i++)
//{
//    a[i][0] = 1;
//    a[i][i] = 1;
//}
//for ( i = 1; i < 6; i++)
//{
//    for ( j = 1; j <= i-1; j++)
//    {
//        a[i][j] = a[i-1][j] + a[i-1][j-1];
//    }
//}
//for ( i = 0; i < 6; i++)
//{
//    for ( j = 0; j < i +1; j++)
//    {
//        printf("%3d",a[i][j]);
//    }
//    printf("\n");
//}
//int a[6][6] , i , j;
//for ( i = 0; i < 6; i++)
//{
//    for ( j = 0; j <= i; j++)
//    {
//            if(j == i || j == 0)
//                a[i][j] = 1;
//            else
//                a[i][j] = a[i-1][j] + a[i-1][j-1];
//    }
//}
//for ( i = 0; i < 6; i++)
//{
//    for ( j = 0; j <= i; j++)
//    {
//        printf("%3d",a[i][j]);
//    }
//    printf("\n");
//}
#endif

#if(1)
//int a[10] , *p , *q , temp;
//for ( p = a; p < a+10; p++)
//{
//    scanf("%d",p);
//}
//for ( p = a , q = a + 9; p < q; p++,q--)
//{
//    temp = *p , *p = *q , *q = temp;
//}
//for ( p = a; p < a+10; p++)
//{
//    printf("%4d",*p);
//}


char a[] = "abcdefg" , *p , *q ,temp;
int m;
m = strlen(a);
for ( p = a , q = a+m-1; p < q; p++ ,q--)
{
    temp = *q , *q = *p ,*p = temp;
}
    puts(a);

#endif        //逆序输出整数数组 和 字符数组

#if(0)
char a[10] , b[10] ,c[10];
printf("请输入两个字符串：\n");
gets(a);
gets(b);
if(strlen(a) < strlen(b) )
{
    strcpy(c,a),strcpy(a,b),strcpy(b,c);
}    
    puts(a);
    puts(b);
#endif    //把较短的字符串放在a数组，较长的字符串放在b数组。并输出

#if(0)
    char s1[80] , s2[40];
    int i = 0 , j = 0;
    gets(s1);
    gets(s2);
    /*字符串复制*/
    //while ((s1[i++] = s2[j++]) != '\0');
    //puts(s1);
    /*字符串拼接*/
    while (s1[i] != '\0') i++;
    while ((s1[i++] = s2[j++]) != '\0');
    s1[i] = '\0';
    puts(s1);
#endif    //字符串复制 和 字符串拼接

#if(0)
    char a[10], b[10];
    int m;
    int i;
    gets(a);
    gets(b);
    for ( i = 0; a[i] != '\0' && b[i] != '\0' ; i++)
    {
        if(a[i] == b[i]) continue;
        else
        {
            m = a[i] - b[i];
            break;
        }
    }
    printf("%d\n",m);
#endif    //输入的两个字符串进行比较，然后输出两个字符串中第一个不相同字符的ASCII码之差

#if(0)
int num[26],i;
char c;
for ( i = 0; i < 26; i++)
{
    num[i] = 0;
}
while ((c = getchar()) != '#')
{
    if(isupper(c)) num[c-65] += 1;
}
for ( i = 0; i < 26; i++)
{
    if(num[i])
        printf("%c：%d\n",i+65,num[i]);
}
#endif    //使其的功能是统计从终端输入字符中每个大写字母的个数。用#号作为输入结束标志

#if(0)
//char a[10];
//int i;
//gets(a);
//for ( i = 0; a[i]!= '\0'; i++)
//{
//    if(a[i]>'0')
//     printf("%d",a[i]-'0');
//    else
//     printf("-");
//    continue;
//}

int m , a[10], j = 0 , i;
char b[10];
scanf("%d",&m);
do
{
     a[j] = m % 10;
     m = m / 10;
     j++;
} while (m);

for ( i = j; i >= 0; i--)
{
    printf("%c",a[i-1]+'0');
}
#endif  //字符串转数字 和 数字转字符串



/*************************************************************指针*********************************/
#if(0)
int a[5] = {1,2,3,4,5} , b[5] = {6,7,8,9,10} , c[5], *p , i;
p = c;
for ( i = 0; i < 5; i++)
{
    *(p+i) = a[i];
    a[i] = b[i];
    b[i] = *(p+i);
}
for ( i = 0; i < 5; i++)
{
    printf("%3d",a[i]);
    
}
printf("\n");
for ( i = 0; i < 5; i++)
{
    printf("%3d",b[i]);
}
#endif    //使用指针实现交换数组a和数组b

#if(0)
//void sort123(int *p , int n);
//int a[10] = {1,2,3,4,5,6,7,8,9,10},*p,t,i,j;
//p = a;
//sort123(a,10);
//for ( p = a; p < a+10; p++)
//{
//    printf("%3d",*p);
//}
    char *day[ ] = {"Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"};
    //int today;
    //printf("今天是星期");
    //scanf("%d", &today);
    char **today = day;
    int i;
    for ( i = 0; i < 7; i++)
    {
        printf("%s",*(day + i));
    }
    //switch (today)
    //{
    //case 1:
    //case 2:
    //case 3:
    //case 4:
    //case 5:
    //case 6:
    //case 7:
    //    printf("%s",day[today-1]);
    //    break;
    //}
#endif

#if( 0 )
    int a[3][4] = {{0,1,2,3},{4,5,6,7},{8,9,10,11}};
    int (*p)[4];
    int i,j;
    p = a;
    do
    {
    printf("i = ");
    scanf("%d",&i);
    } while (i >= 3 || i < 0);
    do
    {
    printf("j = ");
    scanf("%d",&j);
    } while (j >= 4 || j < 0);

    printf("a[%d][%d] = %d",i,j,*(*(p+i)+j));
#endif    //通过输入指定行数和列数打印出对应的值

#if(0)
//int a[10],max,min,i,t,*p;
//for ( p = a; p < a + 10; p++)
//{
//    scanf("%d",p);
//}
//max = min = 0;
//p = a;
//for ( i = 0; i < 10; i++)
//{
//    if(*(p+i)>*(p+max))  max = i;
//
//}
//t = *p, *p = *(p+max), *(p+max) = t;
//for ( i = 0; i < 10; i++)
//{
//    if(*(p+i)<*(p+min)) min = i;
//}
//t = *(p+9), *(p+9) = *(p+min), *(p+min) = t;
//for ( p = a; p < a + 10; p++)
//{
//    printf("%3d",*p);
//}
    /*int a[10] , *p , i , max = 0 , min = 0 , t , k;
    p = a;
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",p+i);
    }
    for ( i = 0; i < 10; i++)
    {
        if(*(p+max)<*(p+i)) max = i;
        else if(*(p+min)>*(p+i)) min = i;

    }
    t =*p;
    *p = *(p+max);
    *(p+max) = t;
    k =*(p+9);
    *(p+9)= *(p+min);
    *(p+min) = k;
    for ( i = 0; i < 10; i++)
    {
        printf("%3d",a[i]);
    }*/
#endif    //用指针最大的数和第一个数交换，最小的数最后一个数交换

//int a[10] , *p , i , j ,m;
//
//for ( p = a; p < a+10; p++)
//{
//    scanf("%d",p);
//}
//p = a;
//j = 10 - 1 / 2;
//for ( p = a + 9; p < p + j; p--)
//{
//
//}
/*************************************************************指针*********************************/
#if(0)
int x , a[5] , i = 0  , j;
scanf("%d",&x);
while (x)
{
     a[i] = x % 10;
     x = x / 10;
     i++;
}
printf("total is %d\n",i);
for ( j = 0; j < i; j++)
{
    printf("%3d",a[j]);
}
#endif    //输入一个不多于五位数的正整数，判断它是几位，并逆序输 出各位数字。

//编写一个程序，将将两个字符串连接起来，不能使用 strcat 函数。

#if(0)
int a[N] = {1,1} , i;
for ( i = 2; i < N; i++)
{
    a[i] += a[i -1] + a[i-2];
}
for ( i = 0; i < N; i++)
{
    printf("%5d",a[i]);
}

#endif    //斐波拉契

#if(0)
        int m , i , k , n = 0;
        for ( m = 2; m <= 500; m++)
        {
            k = (int)sqrt((double)m);
            for ( i = 2; i <= k; i++)
            {
                if(m % i == 0) break;
            }
            if ( i > k ) 
            {printf("%4d",m); n = n+1; if(n%5==0) printf("\n");}
        }
                printf("total is %d",n);
#endif  //打印500以内的素数

#if(0)
//辗转相除法
//int a,b,t;
//scanf("%d %d",&a,&b);
//while (b != 0)
//{
//    t = a % b;
//    a = b;
//    b = t;
//}
//printf("最大公约数是%d",a);

//更相减损法
//int a,b,t;
//scanf("%d %d",&a,&b);
//while (a != b)
//{
//    if(a>b) 
//    {
//        a -= b;
//    }else
//    {
//        b -= a;
//    }
//}
//printf("最大公约数是%d",a);

//int x, y, gcd;
//    printf("请输入两个正整数：");
//    scanf("%d%d", &x, &y);
//    if(x < y)
//        gcd = x;
//    else
//        gcd = y;
//    while(x % gcd ||y % gcd)
//        gcd--;
//    printf("gcd = %d\n", gcd);

//int a , b , i , t;
//scanf("%d %d",&a,&b);
//for ( i = 1; i <= a || i <= b; i++)
//{
//    if(    a % i == 0 && b % i == 0 ) t = i;
//}
//    printf("%d",t);

//递归

int gcd1(int x , int y);
int a,b,result;
scanf("%d %d",&a,&b);
result = gcd1(a,b);
printf("最大公约数%d",result);
#endif //最大公约数

#if(0)
int a[5] = {12,18,1,0,6} , min , max, i , j , k , t; 
max = min = a[0];

for ( i = 0; i < 5; i++)
{
    if(a[i]<min)
    { min = a[i] , k = i;}
    else if(a[i]>max)
    {
        max = a[i] , j = i;
    }
}
//t = a[4];
//a[4] = a[k];
//a[k] = t;
//
//t = a[0];
//a[0] = a[j];
//a[j] = t;
a[k] = max;
a[j] = min;
for ( i = 0; i < 5; i++)
{
    printf("%3d",a[i]);
}
#endif  //最大值和最小值的位置进行调换

#if(0)
int i , j ,temp ,a[5];
int hight , low , mid , nummber;
hight = 4;
low = 0;
for ( i = 0; i < 5; i++)
{
    scanf("%d",&a[i]);
}
for ( i = 0; i < 4; i++)
{
    for ( j = 0; j < 4 - i; j++)
    {
        if(a[j+1]>a[j])
        {
            temp = a[j];
            a[j] = a[j+1];
            a[j+1] = temp;
        }
    }
}

printf("数组元素的值为：\n");
for ( i = 0; i < 5; i++)
{
    printf("%3d",a[i]);
}
printf("请输入要查找的数\n");
scanf("%d",&nummber);
if((nummber > a[0])||(nummber < a[4]))
    printf("cannot find %d\n",nummber);
else
{
    while (low <= hight)
    {
        mid = (low+hight)/2;
        if(a[mid] == nummber)
        {printf("This number %d is find, position is %d\n",mid+1,nummber); break;}
        else if(nummber>a[mid]) low = mid + 1;
        else hight = mid -1;
    }
        if(a[mid] != nummber) 
        printf("Not found this number %d\n",nummber);
}
#endif   //二分法求位置

#if(0)
    int a[10] ,i , j , k , max ,temp, b[9];
    max = a[0];
    for ( i = 0; i < 10; i++)
    {
        scanf("%d",&a[i]);
            for ( j = 0; j < i ; j++)
            {
                while (a[i] == a[j])
                {
                    printf("请重新输入\n");
                    scanf("%d",&a[i]);
                }
            }
    }
    for ( i = 0; i < 9; i++)
    {
        for ( j = 0; j < 9; j++)
        {
            if(a[j]>a[j+1]) 
            {
                temp = a[j];
                a[j] = a[j+1];
                a[j+1] = temp;
            }
        }
    }
    printf("最大值是%d\n",a[9]);
    printf("删除后的数组元素是：\n");
    for ( i = 0; i < 9; i++)
    {
        b[i] = a[i];
        printf("%3d",b[i]);
    }
#endif     //输入10个互不相同的实数并存到数组，找出最大值，并删除

#if(0)
    int a[4] = {1,3,5,10}, b[5] = {2,4,6,8,9}, c[1000] , i = 0, j = 0 , k=0;


        while (j < 4 || k < 5 || i<9)
        {
            if(a[j] < b[k]) 
            {    c[i] = a[j]; }
            else
            {
                c[i] = b[j]; 
            }
            j++ , k++ , i++;
        }
    

    
    for ( i = 0; i < 9; i++)
    {
        printf("%3d",c[i]);
    }
#endif

#if(0)
    //int a[10],i,j,t;
    //printf("Please input 10 numbers: ");
    //for(i=0;i<10;i++)
    //scanf("%d",&a[i]);
    //for(i=1;i<10;i++) /*外循环控制趟数，n个数从第2个数开始到最后共进行n-1次插入*/
    //{
    //t=a[i]; /*将待插入数暂存于变量t中*/
    //for( j=i-1 ; j>=0 && t<a[j] ; j-- ) /*在有序序列（下标0 ~ i-1）中寻找插入位置*/
    //a[j+1]=a[j]; /*若未找到插入位置，则当前元素后移一个位置*/
    //a[j+1]=t; /*找到插入位置，完成插入*/
    //}
    //printf("The sorted numbers: ");
    //for(i=0;i<10;i++)
    //printf("%d ",a[i]);
    //printf("\n");
    //int a[5] = {1,3,5,2,4} , i , j ,k, temp;
    //for ( i = 1; i <= 5; i++)
    //{
    //    for ( j = 0; j < 5 - i; j++)
    //    {
    //        if(a[j+1]<a[j])
    //        {
    //            temp = a[j];
    //            a[j] = a[j+1];
    //            a[j+1] = temp; 
    //        }
    //    }
    //}
    //for ( i = 0; i < 5; i++)
    //{
    //    printf("%3d",a[i]);
    //}


    //for ( i = 0; i < 4; i++)
    //{
    //     k = i;
    //    for ( j = i + 1; j < 5; j++)
    //    {
    //        if(a[k] > a[j] ) k = j;
    //    }
    //    if(k!=i)
    //    {
    //        temp = a[i];
    //        a[i] = a[k];
    //        a[k] = temp;
    //    }
    //}
    //for ( i = 0; i < 5; i++)
    //{
    //    printf("%3d",a[i]);
    //}

    //for ( i = 1; i < 5; i++)
    //{
    //    temp = a[i];
    //    for ( j = i - 1; j >=0 && a[j] > temp; j--)
    //    {
    //        a[j+1] = a[j];
    //        a[j] = temp;
    //    }
    //}
    //for ( i = 0; i < 5; i++)
    //{
    //    printf("%3d",a[i]);
    //}
#endif  //排序

    //char *a[2] = {"one","two"},**p = a;
    //printf("%s\n",*(p++)+1);
    //printf("%c\n",**p-1);
#if(0)
    char str[N][10] , max[10];
    int i , n;
    printf("total input string is ：");
    scanf("%d",&n);
    getchar();            //吃掉缓存区的回车字符
    for ( i = 0; i < n; i++)
    {
        gets(str[i]);

    }
        strcpy(max,str[0]);
    for ( i = 1; i < n; i++)
    {
        if(strcmp(str[i],max)>0) strcpy(max,str[i]);
    }
    printf("最大的字符串是%s",max);
#endif        //用二维数组求最大字符串

#if(0)
    char st[10],cs[][10] ={"Monday","Tuseday","Wednesday","Thursday","Friday","Saturday","Sunday"} ,i ,k ,j;
    for ( i = 0; i < 6; i++)
    {
          k = i;
          for ( j = i + 1 ; j < 7; j++)
          {
              if(strcmp(cs[k],cs[j])>0) k = j;
          }
          if(k != i)
          {
              strcpy(st,cs[i]); strcpy(cs[i],cs[k]); strcpy(cs[k],st);
          }
    }
    for ( i = 0; i < 7; i++)
    {
        puts(cs[i]);
    }
#endif        //将二维字符数组储存的字符串按从小到大顺序排序并且输出这些字符串

#if(0)
    int a[3][4] =  {1,2,3,4,5,6,7,8,9,10,11,12};
    int *pa[3] = {a[0],a[1],a[2]};
    int i , j;
    for ( i = 0; i < 3; i++)
    {
        for ( ;pa[i] <a[i+1]; pa[i]++)   //p
        {
            printf("%d\t",*pa[i]);
        }
        printf("\n");
    }
#endif    //通过一个指针数组来指向一个二维数组，指针数组中的每个元素被赋予二维数组每一行的首地址

#if(0)
    char *w[] = {"Monday","Tuseday","Wednesday","Thursday","Friday","Saturday","Sunday"};
    char *st;
    int i , j ,k;
    printf("排序前的字符串地址，字符串的值如下：\n");
    for ( i = 0; i < 7; i++)
    {
        printf("%s\n",w[i]);
    }
    for ( i = 0; i < 7; i++)
    {
        k = i;
        for ( j = i+1; j < 7; j++)
        {
            if(strcmp(w[j],w[k])<0) k = j;
        }
        if(k!=i)
        {
            st = w[i]; w[i] = w[k]; w[k] = st;
        }
    }
    printf("排序后的字符串地址，字符串的值如下：\n");
    for ( i = 0; i < 7; i++)
    {
        printf("%s\n",w[i]);
    }
#endif    //将字符指针数组存储的字符串按从小到大的顺序排序且输出

#if(0)
    int i , m , n;
    for ( i = 1; i < 99; i++)
    {
        m = i*i;
        if(i<10)
        {
            n = m % 10;
            if(n == i) printf("%2d %2d \n",m,i);
        }else
        {
            n = m % 100;
            if(n == i) printf("%2d %2d \n",m,i);
        }
    }
#endif    //同构数
    
    //int a[3] = {1,3,12} ,b[5] = {2,4,5,9,7} , c[10] , i = 0 , j = 0 ,k = 0;
    //while (i<3 && j<5)
    //{
    //    if(a[i]<b[j]) { c[k] = a[i]; k++; i++;}
    //    else
    //    {
    //         c[k] = b[j]; k++; j++;
    //    }
    //}
    //while(i<3) { c[k] = a[i]; k++; i++;}
    //while(j<5) {c[k] = b[j]; k++; j++;}
    //for ( i = 0; i < k; i++)
    //{
    //    printf("%3d",c[i]);
    //}

#if(0)
    char a[80];
    int mystrlen(char *a) , length;
    gets(a);
    length = mystrlen(a);
    printf("%d",length);
#endif        //自定义字符串长度函数

#if(0)
    char a[10] , b[10];
    void mystrcpy(char *p1 , char *p2);
    gets(a);
    gets(b);
    mystrcpy(a,b);
    puts(a);
#endif        //自定义字符串复制函数

    //int i , j , a[6][6];
    //for ( i = 0; i < 6; i++)
    //{
    //    for ( j = 0; j <= i; j++)
    //    {
    //        if(i<=1)  a[i][j] = 1;
    //        else
    //        {
    //            if(i == 0 || i == j)  a[i][j] = 1;
    //            if(j > 0 && i > j)
    //            {
    //                 a[i][j] = a[i-1][j]+a[i-1][j-1];
    //            }
    //        }
    //    }
    //}
    //for ( i = 0; i < 6; i++)
    //{
    //    for ( j = 0; j <= i; j++)
    //    {
    //        printf("%d",a[i][j]);
    //    }
    //    printf("\n");
    //}
    
}
int gcd1(int x , int y)
{
    if( x % y == 0) return y;
    else return gcd1(y, x % y);
}

int mystrlen(char *p)
{
    int i , length = 0;
    //for ( i = 0; *(p+i) != '\0'; i++)      //*(p+i) 或 p[i]
    //{
    //    length++;
    //}
    while (*p++!='\0')
    {
        length++;
    }
    return length;
}

void mystrcpy(char *p1 , char *p2)
{
    int i = 0;
    while (p2[i] != '\0')
    {
        p1[i] = p2[i];
        i++;
    }
    p1[i] = '\0'; 
    //while ((*p1++ = *p2++)!= '\0');

}

void sort123(int *p , int n)
{
    //int i , j , t;
    //for ( i = 0; i < n-1; i++)
    //{
    //    for ( j = 0; j < n-i-1; j++)
    //    {
    //        if(a[j]<a[j+1])
    //        {
    //           t = a[j];
    //           a[j] = a[j+1];
    //           a[j+1] = t;
    //        }
    //    }
    //}

    int i ,j ,t;
    for ( i = 0; i < n-1; i++)
    {
        for ( j = 0; j < n-i-1; j++)
        {
            if(*(p+j)<*(p+j+1))
            {
                t = *(p+j);
                *(p+j) = *(p+j+1);
                *(p+j+1) = t;
            }
        }
    }
}