C_TA_Website/source/_posts/answer8.md

title	date	tags
第八次作业（答案）	2020-12-08 16:29:01

P292-10

#include <stdio.h>

void swap(int array[], int i, int j)
{
    int tmp = array[i];
    array[i] = array[j];
    array[j] = tmp;
}

int main(void)
{
    int mat[5][5];
    printf("请输入5x5矩阵的25个元素：\n");
    for (int i = 0; i < 5; ++i) {
        for (int j = 0; j < 5; ++j) {
            scanf("%d", &mat[i][j]);
        }
    }
    int* array = *mat;
    for (int i = 0; i < 4; ++i) {
        int min = array[0];
        for (int j = i + 1; j < 25; ++j) {
            if (array[j] < array[i]) {
                swap(array, i, j);
            }
        }
    }
    int max = array[5];
    for (int i = 4; i < 25; ++i) {
        if (array[i] > max) {
            max = array[i];
        }
    }
    printf("%5d     %5d\n     %5d     \n%5d     %5d\n", array[0], array[1], max, array[2], array[3]);
    return 0;
}

P292-12

#include <stdio.h>
#include <string.h>

void sort_str(char* str[], int n)
{
    for (int i = 0; i < n - 1; ++i) {
        int done = 1;
        for (int j = 0; j < n - i - 1; ++j) {
            if (strcmp(str[j], str[j + 1]) > 0) {
                char* tmp = str[j + 1];
                str[j + 1] = str[j];
                str[j] = tmp;
                done = 0;
            }
        }
        if (done) {
            break;
        }
    }
}

int main(void)
{
    char inputs[5][100];
    for (int i = 0; i < 5; ++i) {
        fgets(inputs[i], 100, stdin);
    }
    char* str[5];
    for (int i = 0; i < 5; ++i) {
        str[i] = inputs[i];
    }
    sort_str(str, 5);
    for (int i = 0; i < 5; ++i) {
        printf("%s", str[i]);
    }
    return 0;
}

P292-14

#include <stdio.h>

void reverse(int n)
{
    int m;
    scanf("%d", &m);
    if (n > 1) {
        reverse(n - 1);
    }
    printf("%d ", m);
}

int main(void)
{
    printf("请问几个数？\nn = ");
    int n;
    scanf("%d", &n);
    printf("请依次输入这些数：\n");
    reverse(n);
    printf("\n");
    return 0;
}

P292-17

#include <stdio.h>

int strcmp(char* p1, char* p2)
{
    for (int i = 0;; ++i) {
        if (p1[i] == '\0') {
            if (p2[i] == '\0') {
                return 0;
            }
            return -1;
        }
        if (p2[i] == '\0') {
            return 1;
        }
        if (p1[i] > p2[i]) {
            return 1;
        }
        if (p1[i] < p2[i]) {
            return -1;
        }
    }
}

int main(void)
{
    char a[100], b[100];
    fgets(a, 100, stdin);
    fgets(b, 100, stdin);
    printf("%d\n", strcmp(a, b));
    return 0;
}

PPT第80页思考题

#include <stdio.h>

int (*seek(int (*pnt_row)[3]))[3]
{
    int i = 0, (*ret_row)[3];
    ret_row = pnt_row + 1;
    for (; i < 3; i++) {
        if (pnt_row[0][i] < 60) {
            ret_row = pnt_row;
            break;
        }
    }
    return ret_row;
}

int main()
{
    int grade[3][3] = { { 55, 65, 75 }, { 65, 75, 85 }, { 75, 80, 90 } };
    int i, j, (*pointer)[3];
    for (i = 0; i < 3; i++) {
        pointer = seek(grade + i);
        if (pointer == grade + i) {
            printf("No. %d grade list: ", i + 1);
            for (j = 0; j < 3; j++) {
                printf("%d ", pointer[0][j]);
            }
            printf("\n");
        }
    }
}