C Primer Plus学习笔记 第10章 编程练习

第一题

#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    PAINFALL   (inches)\n");
    for (year = 0, total = 0; year < YEARS; year++) {
        for (month = 0, subtot = 0; month < MONTHS; month++) {
            // 修改取值放hi是，用指针取值
            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++) {
            // 修改取值放hi是，用指针取值
            subtot += *(*(rain + year) + month);
        }
        printf("%4.1f ",subtot / YEARS);    // 每个月的平均降水量
    }
    printf("\n");
    
    return 0;
    
}

第二题

#include <stdio.h>

void copy_arr(double target1[], double source[], int n);
void copy_ptr(double target2[], double source[], int n);
void copy_ptrs(double [], double [], double * last);


int main(void)
{
    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);
    

    
    printf("source %p; target1 %p, target2 %p target3 %p.\n", source, target1, target2, target3);
    printf("All index 1 is source %f; taeget1 %f; target2 %f target3 %f.\n", *source, target1[0], *target2, target3[0]);
    
    return 0;
}
void copy_arr(double target1[], double source[], int n)
{
    int i;
    for (i = 0; i < n; i++) {
        target1[i] = source [i];
    }
}

// 记住一点，C语言函数对任何一个传进来的参数，都会进行一次拷贝，这样就可以保证，函数不会改变外部的参数。
void copy_ptr(double target2[], double source[], int n)
{
    int i;
    for (i = 0; i < n; i++, source++) {
        *(target2 + i) = *source;
    }
}

void copy_ptrs(double target3[], double source[], double * last)
{
    for (; source < last; target3++, source++) {
        *(target3) = *(source);
    }
    
}

输出

source 0x7ffeefbff460; target1 0x7ffeefbff430, target2 0x7ffeefbff400 target3 0x7ffeefbff3d0.

All index 1 is source 1.100000; taeget1 1.100000; target2 1.100000 target3 1.100000.

第三题

#include <stdio.h>
#define MEMBER_NUMBER 5

int max_number(int [], int);

int main(void)
{
    int ar[MEMBER_NUMBER] = {1, 9, 2, 4, 1};
    int number;
    number = max_number(ar, MEMBER_NUMBER);
    printf("The max number is %d.\n", number);
    
    return 0;
}

int max_number(int ar[], int n)
{
    int max_num , i;
    for (i = 0, max_num = ar[i]; i < n; i++) {
        max_num = (max_num > ar[i]) ? max_num : ar[i];
    }
    return max_num;
}

输出

The max number is 9.

Program ended with exit code: 0

第四题

#include <stdio.h>

#define MEMBER_NUMBER 5

 

int max_index(double [], int);

 

int main(void)

{

    double ar[MEMBER_NUMBER] = {1., 91.2, 12., 4., 11.12};

    int index;

    index = max_index(ar, MEMBER_NUMBER);

    printf("The max index is %d.\n", index);

    

    return 0;

}

 

int max_index(double ar[], int n)

{

    int i, index;

    double max_num;

    for (i = index = 0, max_num = ar[i]; i < n; i++) {

        if (ar[i] > max_num) {

            index = i;

            max_num = ar[i];

        }

    }

    return index;

}

 

输出

The max index is 1.

第五题

#include <stdio.h>
#define MEMBER_NUMBER 5

double max_diff(double [], int);

int main(void)
{
    double ar[MEMBER_NUMBER] = {3.99, 9., 12., 4., 11.12};
    double res;
    res = max_diff(ar, MEMBER_NUMBER);
    printf("The max gap is %.2f.\n", res);
    
    return 0;
}

double max_diff(double ar[], int n)
{
    int i;
    double max_number, min_number;
    for (max_number = min_number = *ar, i = 0; i < n; i++) {
        max_number = (max_number > ar[i]) ? max_number : ar[i];
        min_number = (min_number < ar[i]) ? min_number : ar[i];
    }
    return max_number - min_number;
}

 

输出

The max gap is 8.01.

第六题

#include <stdio.h>
#define MEMBER_NUMBER 4

void reveres(double [], int);

void show(double ar[], int n);

int main(void)
{
    double ar[MEMBER_NUMBER] = {91.2, 12., 4., 11.12};
    reveres(ar, MEMBER_NUMBER);
    printf("The max index is .\n");
    show(ar, MEMBER_NUMBER);
    return 0;
}

// 用一个临时变量接受
void reveres(double ar[], int n)
{
    int i;
    double temporary_number;
    for (i = 0; i < n / 2; i++) {
        temporary_number = ar[i];
        ar[i] = ar[n-i-1];
        ar[n-i-1] = temporary_number;
    }
}

void show(double ar[], int n)
{
    int i;
    for (i = 0; i < n; i++) {
        printf("%f ", ar[i]);
    }
    printf("end.\n");
}

 

第七题

 

#include <stdio.h>

void copy_arr(double target1[], double source[], int n);
void copy_ptr(double target2[], double source[], int n);
void copy_ptrs(double [], double [], double * last);


int main(void)
{
    double source[5] ={1.1, 2.2, 3.3, 4.4, 5.5};
    double target1[5];
    double target2[5];
    double target3[5];
    double source_two[2][3]= {1, 2, 3, 4, 5, 1};
    double target4[2][3];
    
    
    copy_arr(target1, source, 5);
    copy_ptr(target2, source, 5);
    copy_ptrs(target3, source, source + 5);
    // 分两次处理，第一次出来第一行，第二次处理第二行。
    copy_ptr(target4[0], source_two[0], 3);
    copy_ptr(target4[1], source_two[1], 3);
    printf("%f\n", target4[1][2]);

    
    printf("source %p; target1 %p, target2 %p target3 %p.\n", source, target1, target2, target3);
    printf("All index 1 is source %f; taeget1 %f; target2 %f target3 %f.\n", *source, target1[0], *target2, target3[0]);
    
    return 0;
}
void copy_arr(double target1[], double source[], int n)
{
    int i;
    for (i = 0; i < n; i++) {
        target1[i] = source [i];
    }
}

// 记住一点，C语言函数对任何一个传进来的参数，都会进行一次拷贝，这样就可以保证，函数不会改变外部的参数。
void copy_ptr(double target2[], double source[], int n)
{
    int i;
    for (i = 0; i < n; i++, source++) {
        *(target2 + i) = *source;
    }
}

void copy_ptrs(double target3[], double source[], double * last)
{
    for (; source < last; target3++, source++) {
        *(target3) = *(source);
    }
    
}

第八题

 double source_7[7] = {1, 2, 3, 4, 5, 6, 7};
    double target_3[3];
    
    copy_arr(target_3, source_7+2, 3);
    printf("%f\n", target_3[2]);

复制了中间一小段代码

第九题

#include <stdio.h>
#define ROWS 3
#define COLUMNS 5

void copy_arr(int r, int c, double soucre[r][c], double target[r][c]);
void show_arr(int r, int c, double soucre[r][c], double target[r][c]);
int main(void)
{
    int row = 3, col = 5;
    double s_arr[ROWS][COLUMNS] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
    double t_arr[row][col];
    copy_arr(row, col, s_arr, t_arr);
    show_arr(row, col, s_arr, t_arr);
    return 0;
}

// 拷贝数组
void copy_arr(int r, int c, double soucre[r][c], double target[r][c])
{
    int nr, nc;
    for (nr = 0; nr < r; nr++) {
        for (nc = 0; nc < c; nc++) {
            target[nr][nc] = soucre[nr][nc];
        }
    }
}

// 显式数组
void show_arr(int r, int c, double soucre[r][c], double target[r][c])
{
    int nr, nc;
    for (nr = 0; nr < r; nr++) {
        for (nc = 0; nc < c; nc++) {
            printf("%f ", soucre[nr][nc]);
        }
    }
    putchar('\n');
    for (nr = 0; nr < r; nr++) {
        for (nc = 0; nc < c; nc++) {
            printf("%f ", target[nr][nc]);
        }
    }
    putchar('\n');
    
}

第十题

#include <stdio.h>
#define COUNT 4

void sum_arr(int add1[], int add2[], int res[], int n);
void show(int ar[], int n);

int main(void)
{
    int ar1[COUNT] = {1, 2, 3, 4};
    int ar2[COUNT] = {4, 3, 2, 1};
    int res[COUNT];
    
    sum_arr(ar1, ar2, res, COUNT);
    show(res, COUNT);
    
    return 0;
    
}

void sum_arr(int add1[], int add2[], int res[], int n)
{
    int i;
    for (i = 0; i < n; i++) {
        res[i] = add1[i] + add2[i];
    }
    
}


void show(int ar[], int n)
{
    int i;
    for (i = 0; i < n; i++) {
        printf("%d ", ar[i]);
    }
    printf("\n*** end *** \n");
}

第十一题

#include <stdio.h>
#define ROWS 3
#define COLUMNS 5


void arr_double(int ar[][COLUMNS], int n);
void show(int ar[][COLUMNS], int n);

int main(void)
{
    int ar[ROWS][COLUMNS] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
    show(ar, ROWS);
    arr_double(ar, ROWS);
    show(ar, ROWS);
    
    return 0;
    
}

// 原数值翻倍
void arr_double(int ar[][COLUMNS], int n)
{
    int r, c;
    for (r = 0; r < n; r++) {
        for (c = 0; c < COLUMNS; c++) {
            ar[r][c] *= 2;
        }
    }
}


// 显式数值
void show(int ar[][COLUMNS], int n)
{
    int r, c;
    for (r = 0; r < n; r++) {
        for (c = 0; c < COLUMNS; c++) {
            printf("%d ", ar[r][c]);
        }
        printf("\n");
    }
    printf("\n*** end *** \n");
}

第十二题

#include <stdio.h>
#define MONTHS 12
#define YEARS 5

void show_year_info(const double rain[][MONTHS], int row);
void show_month_info(const double rain[][MONTHS], int row);

int main(void)
{
    const double 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}
    };
    
    show_year_info(rain, YEARS);
    show_month_info(rain, YEARS);
    
    
    return 0;
    
}

// 记得函数定义const，因为传入的指针就定义了const
void show_year_info(const double rain[][MONTHS], int row)
{
    float subtot, total;
    int year, month;
    printf("YEAR    PAINFALL   (inches)\n");
    for (year = 0, total = 0; year < row; year++) {
        for (month = 0, subtot = 0; month < MONTHS; month++) {
            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);
}


void show_month_info(const double rain[][MONTHS], int row)
{
    float subtot;
    int year, month;
    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 < row; year++) {
            subtot += rain[year][month];
        }
        printf("%4.1f ",subtot / YEARS);    // 每个月的平均降水量
    }
    printf("\n");
}

第十三题

#include <stdio.h>
#define ROWS 3
#define COLUMNS 5

void scanf_elemet(double ar[][COLUMNS], int row);
double average_serier(const double ar[], int columns);
double average_all(double ar[][COLUMNS], int row);
double max_number(double ar[][COLUMNS], int row);
void show(double ar[][COLUMNS], int n);

int main(void)
{
    int i;
    
    double ar[ROWS][COLUMNS];
    scanf_elemet(ar, ROWS);
    for (i = 0; i < ROWS; i++) {
        average_serier(ar[i], COLUMNS);
    }
    average_all(ar, ROWS);
    max_number(ar, ROWS);
    show(ar, ROWS);
    
    return 0;
}

//找出最大值
double max_number(double ar[][COLUMNS], int row)
{
    int r, c;
    double max_num;
    for (r = 0, max_num = **ar; r < row; r++) {
        for (c = 0; c < COLUMNS; c++) {
            max_num = (max_num > ar[r][c]) ? max_num : ar[r][c];
        }
    }
    printf("The max number is %g.\n", max_num);
    
    return max_num;
    
}

/* 计算所有值的平均值 */
double average_all(double ar[][COLUMNS], int row)
{
    int r, c;
    double total, aver_num;
    for (r = 0, total = 0; r < row; r++) {
        for (c = 0; c < COLUMNS; c++) {
            total += ar[r][c];
        }
    }
    
    aver_num = total / (row * COLUMNS);
    printf("All average is %g.\n", aver_num);
    
    return aver_num;
}


// 计算以为数组的平均值，调用三次
double average_serier(const double ar[], int colums)
{
    int i;
    double total, aver_num;
    for (i = 0, total = 0; i < colums; i++) {
        total += ar[i];
    }
    
    aver_num = total / colums;
    printf("average is %g.\n", aver_num);
    
    return aver_num;
}

// 接受15个数组的输入
void scanf_elemet(double ar[][COLUMNS], int row)
{
    
    int r, c;
    
    for (r = 0; r < row; r ++) {
        printf("Please enter the %d float number:\n", COLUMNS);
        for (c = 0; c < COLUMNS; c++) {
            scanf("%lf", &ar[r][c]);
        }
    }
}


void show(double ar[][COLUMNS], int n)
{
    int r, c;
    for (r = 0; r < n; r++) {
        for (c = 0; c < COLUMNS; c++) {
            printf("%g ", ar[r][c]);
        }
        printf("\n");
    }
    printf("\n*** end *** \n");
}

第十四题

#include <stdio.h>
#define ROWS 3
#define COLUMNS 5

void scanf_elemet(int row, int column,double ar[row][column]);
double average_serier(const double ar[], int columns);
double average_all(int row, int column,double ar[row][column]);
double max_number(int row, int column,double ar[row][column]);
void show(int row, int column,double ar[row][column]);

int main(void)
{
    int i;
    
    double ar[ROWS][COLUMNS];
    scanf_elemet(ROWS, COLUMNS, ar);
    for (i = 0; i < ROWS; i++) {
        average_serier(ar[i], COLUMNS);
    }
    average_all(ROWS, COLUMNS, ar);
    max_number(ROWS, COLUMNS, ar);
    show(ROWS, COLUMNS, ar);
    
    return 0;
}

//找出最大值
double max_number(int row, int column,double ar[row][column])
{
    int r, c;
    double max_num;
    for (r = 0, max_num = **ar; r < row; r++) {
        for (c = 0; c < column; c++) {
            max_num = (max_num > ar[r][c]) ? max_num : ar[r][c];
        }
    }
    printf("The max number is %g.\n", max_num);
    
    return max_num;
    
}

/* 计算所有值的平均值 */
double average_all(int row, int column,double ar[row][column])
{
    int r, c;
    double total, aver_num;
    for (r = 0, total = 0; r < row; r++) {
        for (c = 0; c < column; c++) {
            total += ar[r][c];
        }
    }
    
    aver_num = total / (row * COLUMNS);
    printf("All average is %g.\n", aver_num);
    
    return aver_num;
}


// 计算以为数组的平均值，调用三次
double average_serier(const double ar[], int colums)
{
    int i;
    double total, aver_num;
    for (i = 0, total = 0; i < colums; i++) {
        total += ar[i];
    }
    
    aver_num = total / colums;
    printf("average is %g.\n", aver_num);
    
    return aver_num;
}

// 接受15个数组的输入
void scanf_elemet(int row, int column,double ar[row][column])
{
    
    int r, c;
    
    for (r = 0; r < row; r ++) {
        printf("Please enter the %d float number:\n", COLUMNS);
        for (c = 0; c < column; c++) {
            scanf("%lf", &ar[r][c]);
        }
    }
}


void show(int row, int column,double ar[row][column])
{
    int r, c;
    for (r = 0; r < row; r++) {
        for (c = 0; c < column; c++) {
            printf("%g ", ar[r][c]);
        }
        printf("\n");
    }
    printf("\n*** end *** \n");
}