慕课-程序设计与算法（大学先修课)-郭炜-第八九周练习题

1.下面程序片段的输出结果是 Hello ,请填空

#include 
using namespace std;
int main() {
    char s[] = "Hello";  
    char * p;
    for(p=s;*p!=NULL;p++)
        cout << * p ;
    return 0;
}

2.下面程序输出结果是 Tesla Tes 请填空

#include 
using namespace std;
void Print(const char * p1, const char * p2) 
{  
    for(;p1cout << * p1;
}
int main()  
{
    const char * s = "Tesla123";
    Print(s,s+5);
    cout << endl;
    Print(s,s+3);
    cout << endl;

    return 0;
}

3.程序填空，使得输出结果为：
1,4,9,16,25,
h,e,l,l,o,!,

#include 
using namespace std;

void ForEach(void * a, int width, int num,
void f(void *)
)

{
    for(int i = 0;i < num; ++i) 
        f((char*)a+width*i);
}

void PrintSquare(void * p)
{
    int * q = (int*)p;
    int n = *q;
    cout << n * n << ",";
}
void PrintChar(void * p) {
    char * q = (char*)p;
    cout << *q << ",";
}
int main()
{
    int a[5] = {1,2,3,4,5};
    char s[] = "hello!";
    ForEach(a,sizeof(int),5,PrintSquare); 
    cout << endl;
    ForEach(s,sizeof(char),6,PrintChar);
    return 0;
}

4.Memcpy之一
输入：
第一行是整数t
接下来是t个整数
再接下来是t个不带空格的字符串，长度不超过20
输出：
按原样输出t个整数和t个字符串

#include 
using namespace std;
void Memcpy(char * src,char * dest,int n)
{
    for(int i=0;iint Strlen(char * s)
{   
    int i;
    for( i = 0; s[i]; ++i);
    return i;
}
int main()  
{
    int a;
    char s1[30];
    char s2[30];
    int t;
    cin >> t;
    for(int i = 0;i < t; ++i) {
        cin >> a;
        int b = 99999999;
        Memcpy((char*)&a,(char *) &b,sizeof(int));
        cout << b << endl;
    }
    for(int i = 0;i < t; ++i) {
        cin >> s1;
        Memcpy(s1,s2,Strlen(s1)+1);
        cout << s2 << endl;
    }
    return 0;
}

5.程序填空，使其输出结果是： 1,2,3,4, 10,12,14,16, 18,20,11,12,

#include 
using namespace std;

void Double(int * p, int n)
{
    for(int i = 0;i < n; ++i)
        p[i] *= 2;
}


int main()
{
    int a[3][4] = { { 1,2,3,4},{5,6,7,8},
                    { 9,10,11,12 } };

    Double(
a[1],6
);
    for(int i = 0;i < 3; ++i) {
        for(int j = 0; j < 4; ++j)
            cout << a[i][j] << ",";
        cout << endl; 
    }

    return 0;
}

6.Memcpy之二
输入：
第一行是整数n (1<=n<=10)
第二行是 n个整数
输出：
先原序输出输入数据中的n个整数
然后再输出:
1,2,3,4,5,1,2,3,4,5,
123434567
167896789

#include 
using namespace std;
void Memcpy( void * src, void * dest, int size)
{
char * dest1 = (char *)dest;
    char * src1 = (char *)src;
    for (int i = size-1; i >= 0; i--)
        dest1[i] = src1[i];
}

void Print(int * p,int size)
{
    for(int i = 0;i < size; ++i)
        cout << p[i] << ",";
    cout << endl;
}

int main()
{
    int a[10];
    int n;
    cin >> n;
    for(int i = 0;i < n; ++i)
        cin >> a[i];
    int b[10] = {0};
    Memcpy(a,b,sizeof(a));
    Print(b,n);

    int c[10] = {1,2,3,4,5,6,7,8,9,10};
    Memcpy(c,c+5,5*sizeof(int)); //将c的前一半拷贝到后一半 
    Print(c,10);

    char s[10] = "123456789";
    Memcpy(s+2,s+4,5); //将s[2]开始的5个字符拷贝到s[4]开始的地方 
    cout << s << endl;

    char s1[10] = "123456789";
    Memcpy(s1+5,s1+1,4); //将s1[5]开始的4个字符拷贝到s1[1]开始的地方 
    cout << s1 << endl;


    return 0;
}

7.编写一个 MyMax函数，可以用来求任何数组中的最大值 使得程序按要求输出

#include 
using namespace std;
void *MyMax(void *a, unsigned int b, int n, int(*fun)(void *, void *))
{
    int judge;
    int *max = (int *)a;
    for (int i = 1; iint *)a+i);
        if (judge < 0)
            max = (int *)a + i;
    }
    return max;
}
int Compare1(void * n1,void * n2)
{
    int * p1 = (int * )n1;
    int * p2 = (int * )n2;
    return ((*p1)%10) - ((*p2)%10);
}
int Compare2(void * n1,void * n2)
{
    int * p1 = (int * )n1;
    int * p2 = (int * )n2;
    return *p1 - *p2;
}
#define eps 1e-6
int Compare3(void * n1,void * n2)
{
    float * p1 = (float * )n1;
    float * p2 = (float * )n2;
    if( * p1 - * p2 > eps)
        return 1;
    else if(* p2 - * p1 > eps)
        return -1;
    else
        return 0; 
}

int main()
{
    int t;
    int a[10];
    float d[10];
    cin >> t;
    while(t--) {
        int n;
        cin >> n;
        for(int i = 0;i < n; ++i)
            cin >> a[i];
        for(int i = 0;i < n; ++i)
            cin >> d[i];
        int * p = (int *) MyMax(a,sizeof(int),n,Compare1);
        cout << * p << endl;
        p = (int *) MyMax(a,sizeof(int),n,Compare2);
        cout << * p << endl;
        float * pd = (float * )MyMax(d,sizeof(float),n,Compare3);
        cout << * pd << endl;
    }
    return 0;
}

8.指向指针的指针，程序填空使得输出指定结果

#include 
using namespace std;
int main()
{
    int x,y,z;
    x = 10;
    y = 20;
    z = 30;

    int * a[3]  = { &x, &y,&z};
    for(int *(*p)=a; p < a + 3; ++p) 
            cout<< * (*p) << endl;
    return 0;

}

9.填写内存交换函数 SwapMemory，使得程序输出指定结果

#include 
using namespace std;
void SwapMemory(void * m1,void * m2, int size)
{
if (size > 5)
    {
        int *m11 = (int *)m1;
        int *m22 = (int *)m2;
        int temp;
        for (int i = 0; i < 5; i++)
        {
            temp = *(m11 + i);
            *(m11 + i) = *(m22 + i);
            *(m22 + i) = temp;
        }
    }
    else
    {
        char *m11 = (char *)m1;
        char *m22 = (char *)m2;
        char temp;
        for (int i = 0; i < size; i++)
        {
            temp = *(m11 + i);
            *(m11 + i) = *(m22 + i);
            *(m22 + i) = temp;
        }
    }

}

void PrintIntArray(int * a,int n)
{
    for(int i = 0;i < n; ++i)
        cout << a[i] << ",";
    cout << endl;
}

int main()
{
    int a[5] = {1,2,3,4,5};
    int b[5] = {10,20,30,40,50};
    SwapMemory(a,b,5 * sizeof(int));
    PrintIntArray(a,5);
    PrintIntArray(b,5);
    char s1[] = "12345";
    char s2[] = "abcde";
    SwapMemory(s1,s2,5);
    cout << s1 << endl;
    cout << s2 << endl;
    return 0;
}