c prime plus第十四章练习题

1.

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

int days(char *p);

struct month{
    char name[10];
    char abbrev[4];
    int days;
    int monumb;
};

struct month months[12] = {
    {"janury", "jan", 31, 1},
    {"february", "feb", 28, 2},
    {"march", "mar", 31, 3},
    {"april", "apr", 30, 4},
    {"may", "may", 31, 5},
    {"june", "jun", 30, 6},
    {"july", "jul", 31, 7},
    {"august", "aug", 31, 8},
    {"september", "sep", 30, 9},
    {"october", "oct", 31, 10},
    {"november", "nov", 30, 11},
    {"december", "dec", 31, 12}
};

int main(void)
{
    char input[10];
    int daytotal;

    printf("Enter the name of a month: ");
    while(gets(input) != NULL && input[0] != '\0')
    {
        daytotal = days(input);
        if(daytotal > 0)
            printf("There are 5d days through %s.\n", daytotal, input);
        else
            printf("%s is not valid through %s.\n", daytotal, input);
        printf("Next month (empty line to quit):");
    }
    puts("bye");

    return 0;
}

int days(char *p)
{
    int i = 0, total = 0;
    while(p[i] != '\0')
    {
        p[i] = tolower(p[i]);
        i++;
    }
    for(i = 0; i<12; i++)
    {
        total += months[i].days;
        if(strcmp(p, months[i].name) == 0)
            return total;
    }

    return -1;
}

2.

#include <stdio.h>

int days(int day, int month, int year);
int leapyear(int year);

struct month{
    char name[10];
    char abbrev[4];
    int days;
    int monumb;
};

struct month months[12] = {
    {"janury", "jan", 31, 1},
    {"february", "feb", 28, 2},
    {"march", "mar", 31, 3},
    {"april", "apr", 30, 4},
    {"may", "may", 31, 5},
    {"june", "jun", 30, 6},
    {"july", "jul", 31, 7},
    {"august", "aug", 31, 8},
    {"september", "sep", 30, 9},
    {"october", "oct", 31, 10},
    {"november", "nov", 30, 11},
    {"december", "dec", 31, 12}
};

int main(void)
{
    int day = 1, mon = 12, year = 1, daytotal;
    printf("Enter the number of day,month,year: ");
    while(scanf("%d%d%d", &day, &mon, &year) == 3)
    {
        daytotal = days(day, mon, year);
        if(daytotal > 0)
            printf("There are %d days through day %d, month %d, year%d.\n", daytotal, day, mon, year);
        else
            printf("day %d, month %d, year %d is not valid input.\n", day, mon, year);
        printf("Next month(input q to quit): ") ;
    }
    puts("bye");

    return 0;
}

int days(int day, int mon, int year)
{
    int i, total;
    if(leapyear(year))
        months[1].days = 29;
    else
        months[1].days = 28;
    if(mon <1 || mon > 12 || day < 1 || day > months[mon -1].days)
        return (-1);
    else
    {
        for(i = 0, total = 0; i< mon-1;i++)
            total += months[i].days;
        return (total+day);
    }
}

int leapyear(int year)
{
    if(year %400 == 0)
        return 1;
    else if(year % 100 != 0 && year %4 == 0)
        return 1;
    else
        return 0;
}

3.

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

void sort_title(struct book *p, int count);
void sort_value(struct book *p, int count);

#define MAXTITL 40
#define MAXAUTL 40
#define MAXBKS 100

struct book{
    char title[MAXTITL];
    char author[MAXAUTL];
    float value;
};

int main(void)
{
    struct book library[MAXBKS];
    int count = 0;
    int index;

    printf("Please enter the book title.\n");
    printf("Press [enter] at the start of a line to stop.\n");
    while(count < MAXBKS && gets(library[count].title) != NULL &&
    library[count].title[0] != '\0')
    {
        printf("Now enter the author.\n");
        gets(library[count].author);
        printf("No enter the value.\n");
        scanf("%f", &library[count++].value);
        while(getchar() != '\n')
            continue;
        if(count < MAXBKS)
        printf("Enter the next title.\n");
    }

    if(count > 0)
    {
        printf("Here is the list of your books:\n");
        for(index = 0; index <count; index++)
            printf("%s by %s: $%.2f\n", library[index].title, library[index].author, library[index].value);
        printf("\nHere is the list of your books by title:\n");
        sort_title(&library[0], count);
        for(index = 0; index < count; index++)
            printf("%s by %s: $%.2f\n", library[index].title, library[index].author, library[index].value);    
    }
    else
        printf("No books?Too bad.\n");

    return 0;
}

void sort_title(struct book *p, int count)
{
    int i,j;
    struct book temp;
    for(i = 0; j < count-1; i++)
        for(j = 0; j < count-1-i; j++)
        if(strcmp(p[j].title,p[j+1].title) > 0)
        {
            temp = p[j];
            p[j] = p[j+1];
            p[j + 1] = temp;
        }
}

void sort_value(struct book *p, int count)
{
    int i, j;
    struct book temp;
    for(i = 0; i < count -1; i++)
        for(j = 0; j <count -1-i; j++)
        if(p[j].value > p[j+1].value)
        {
            temp = p[j];
            p[j]= p[j+1];
            p[j+1] = temp;
        }
}

4.