2019 C语言考核参考答案

1.磨铁评级

略

2.库入车倒

#include <stdio.h>

// 第1小题
void reversePrint_13(char *str)
{
    for (int i = 12; i >= 0; i--)
    {
        printf("%c", str[i]);
    }
    printf("\n");
}

int main()
{
    char str[13];
    for (int i = 0; i < 13; i++)
    {
        scanf("%c", &str[i]);
    }
    reversePrint_13(str);
    return 0;
}


// 第2小题
void reversePrint(char *str, int length)
{
    for (int i = length - 1; i >= 0; i--)
    {
        printf("%c", str[i]);
    }
    printf("\n");
}

int main()
{
    char str[1000], c;
    int length = 0;
    while (1)
    {
        c = getchar();
        if (c == '\n'){
            break;
        }
        else
        {
            length++;
            str[length - 1] = c;
        }
    }
    reversePrint(str, length);
    return 0;
}

3.计划生育

#include <stdio.h>

// 递归
// int rabbits(int n)
// {
//     if (n <= 2)
//         return 1;
//     else
//         return rabbits(n - 1) + rabbits(n - 2);
// }

// 非递归
int rabbits(int n)
{
    if (n <= 2)
        return 1;
    else
    {
        int num1 = 1, num2 = 1, index = 3, number = 2;
        for (index = 3; index <= n; index++)
        {
            number = num1 + num2;
            num1 = num2;
            num2 = number;
        }
        return number;
    }
}

int main()
{
    int num = 0, n = 0;
    scanf("%d", &num);
    for (int i = 0; i < num; i++)
    {
        scanf("%d", &n);
        printf("the number in index %d is %d\n", n, rabbits(n));
    }
}

4.指针乱指

#include <stdio.h>
#include <malloc.h>

// 第一小题
void swap(int *num1, int *num2)
{
    int temp;
    temp = *num1;
    *num1 = *num2;
    *num2 = temp;
}

//第二小题
void swap_in_array(int *array, int a1, int a2)
{
    int *p = array;
    int temp;
    temp = *(p + (a1 - 1));
    *(p + (a1 - 1)) = *(p + (a2 - 1));
    *(p + (a2 - 1)) = temp;
}

int main(void)
{
    int num1, num2, n, a1, a2;

    scanf("%d %d", &num1, &num2);
    printf("a is %d and b is %d\n", num1, num2);
    swap(&num1, &num2);
    printf("a is %d and b is %d\n", num1, num2);

    scanf("%d", &n);
    int *array = (int *)malloc(n * sizeof(int));
    int *p = array;
    for (int i = 0; i < n; i++)
    {
        scanf("%d", p);
        p++;
    }
    p = array;
    for (int i = 0; i < n; i++)
    {
        printf("%d ", *p);
        p++;
    }
    printf("\n");
    scanf("%d %d", &a1, &a2);
    swap_in_array(array, a1, a2);
    p = array;
    for (int i = 0; i < n; i++)
    {
        printf("%d ", *p);
        p++;
    }
    printf("\n");
    return 0;
}

5.户口登记

#include <stdio.h>
#include <string.h>
struct person
{
    char name[100];
    int age;
};

typedef struct person Person;

void change_name(Person* p, char *newName)
{
    strcpy(p->name, newName);
}
int main()
{
    Person cxk;
    printf("pls input your age\n");
    scanf("%d", &cxk.age);
    printf("pls input your name\n");
    scanf("%s", &cxk.name);
    printf("my name is %s, age is %d\n", cxk.name, cxk.age);

    printf("pls input your new name\n");
    char newName[100];
    scanf("%s", newName);
    change_name(&cxk, newName);
    // printf("my name is %s, age is %d\n", cxk.name, cxk.age);
    printf("my new name is %s\n", cxk.name);
    return 0;
}

6.进制转换

#include <stdio.h>

int hex(char *a)
{
    for (int i = 0; i < 2; i++)
    {
        if ((a[i] >= 'A' && a[i] <= 'F') || (a[i] >= '0' && a[i] <= '9'))
        {

            if (a[i] >= 'A')
                a[i] = a[i] - 'A' + 10;
            else
                a[i] = a[i] - '0';
        }
        else
        {
            return -1;
        }
    }
    return a[0] * 16 + a[1];
}

int main()
{
    int times, num = 0;
    char a[3];
    scanf("%d", ×);
    for (int i = 0; i < times; i++)
    {
        scanf("%s", a);
        num = hex(a);
        if (num != -1)
        {
            printf("%d\n", num);
        }
        else
        {
            printf("error!\n");
        }
    }
    return 0;
}

7.协议解码

8.算法实现之二分搜索近似计算反正切函数

9.算法实现之：PID

10.算法实现之直方图均衡