C primer plus(第六版） 第十章答案

C primer plus(第六版） 第十章答案

/*  First  */
#include<stdio.h>
#define MONTHS 12
#define YEARS   5
int main(void)
{
   
    const float rain[YEARS][MONTHS] = 
    {
   
        {
    4.3, 4.3, 4.3, 3.0, 2.0, 1.2, 0.2, 0.2, 0.4, 2.4, 3.5, 6.6 },
        {
    8.5, 8.2, 1.2, 1.6, 2.4, 0.0, 5.2, 0.9, 0.3, 0.9, 1.4, 7.3 },
        {
    9.1, 8.5, 6.7, 4.3, 2.1, 0.8, 0.2, 0.2, 1.1, 2.3, 6.1, 8.4 },
        {
    7.2, 9.9, 8.4, 3.3, 1.2, 0.8, 0.4, 0.0, 0.6, 1.7, 4.3, 6.2 },
        {
    7.6, 5.6, 3.8, 2.8, 3.8, 0.2, 0.0, 0.0, 0.0, 1.3, 2.6, 5.2 },

    };
    int year, month;
    float subtot, total;

    printf(" YEAR     RAINFALL  (inches)\n");
    for (year = 0, total = 0; year < YEARS; year++)
    {
   
        for (month = 0, subtot = 0; month < MONTHS; month++)
            subtot += *(*(rain + year) + month);    //原为：subtot += rain[year][month];
        printf("%5d %15.1f\n", 2010 + year, subtot);
        total += subtot;
    }
    printf("\nThe yearly average is %.1f inches.\n\n", total / YEARS);
    printf("MONTHLY AVERAGES:\n\n");
    printf(" Jan Feb Mar Apr May Jun Jul Aug Sep Oct ");
    printf(" Nov Dec\n");

    for (month = 0; month < MONTHS; month++)
    {
   
        for (year = 0, subtot = 0; year < YEARS; year++)
            subtot += *(*(rain + year) + month);
        printf("%4.1f ",subtot / YEARS);
    }
    printf("\n");

    return 0;
}

/*  Second  */
#include<stdio.h>
void copy_arr(double *target, double *source, int n);
void copy_ptr(double *target, double *source, int n);
void copy_ptrs(double *target, double *source_begin, double *source_end);
void print_copy(int n, double *arr);
int main()
{
   
    double source[5] = {
    1.1, 2.2, 3.3, 4.4, 5.5 };
    double target1[5];
    double target2[5];
    double target3[5];

    copy_arr(target1 , source, 5);
    copy_ptr(target2 , source, 5);
    copy_ptrs(target3 , source, source + 5); //到这里已经都copy进去了

    print_copy(1 , target1);
    print_copy(2 , target2);
    print_copy(3 , target3);

    return 0;
}

void copy_arr(double *target, double *source, int n)
{
   
    for (int i = 0; i < n; i++)
        target[i] = source[i]; 
}

void copy_ptr(double *target, double *source, int n)
{
   
    for (int i = 0; i < n; i++)
        *(target + i) = *(source + i);
}

void copy_ptrs(double *target, double *source_begin,  double *source_end)
{
   
    for (double *i = source_begin; i < source_end; i++)
        *(target++) = *i;
}

void print_copy(int n, double *arr)
{
   
    printf("Target%d: ", n );
    for (int i = 0; i < 5; i++)
        printf("%.2lf ",arr[i]);
    printf("\n");
}

/*  Third  */
#include<stdio.h>
int ret_max(int arry[], int n); 
int main