C Primer Plus 第7章 C控制语句：分支和跳转 编程练习

作业练习

1.
#include <stdio.h>
int main(void) {
    char ch;
    int spare, other, n; //空格，其他字符，换行
    spare = other = n = 0;

    while ((ch = getchar()) != '#') {
        if (ch == ' ')
            spare++;
        else if (ch == '\n')
            n++;
        else
            other++;
    }
    printf("spare:%d\nn:%d\nother:%d", spare, n, other);
    return 0;
}

2.
#include <stdio.h>
int main(void) {
    char ch;
    int count;
    while ((ch = getchar()) != '#'){
        printf("%3d ",ch);
        count++;
        if (count % 8 == 0)
            printf("\n");
    }
    return 0;
}

3.
#include <stdio.h>
int main(void) {
    int value, count_o, count_e;
    float odd, even;
    odd = even = count_o = count_e = 0;
    while ((scanf("%d", &value)) == 1 && value != 0) {
        if (value % 2 == 0) {
            odd = odd + value;
            count_o++;
        } else {
            even = even + value;
            count_e++;
        }
    }
    if (count_o > 0)
        printf("odd average:%.2f count:%2d\n", odd / count_o, count_o);
    if (count_e > 0)
    printf("even average:%.2f count:%2d\n", even / count_e, count_e);
    return 0;
}

4.
#include <stdio.h>
int main(void) {
    char ch;
    int count = 0;
    while ((ch = getchar()) != '#'){
        if(ch == '.'){
            ch = '!';
            count++;
        } else if (ch == '!'){
            printf("%c");
            count++;
        }
        printf("%c",ch);
    }
    printf("Number:%d",count);
    return 0;
}

5.
#include <stdio.h>
int main(void) {
    char ch;
    int count = 0;
    while ((ch = getchar()) != '#'){
        switch (ch){
            case '.':ch='!';count++;
                break;
            case '!':printf("%c",ch);count++;
                break;
        }
        printf("%c",ch);
    }
    printf("Number:%d",count);//一共替换了多少次。
    return 0;
}

6.
#include <stdio.h>
int main(void) {
    char ch,ch2,ch3;
    //ch3为前一个字符，ch为当前字符，我真没想到。。
    int count = 0;
    while ((ch=getchar()) != '#'){
        ch3=ch2;ch2=ch;
        if (ch3 == 'e' && ch == 'i')
            count++;
    }
    printf("%d",count);
    return 0;
}

7.
#include <stdio.h>
#define WORK_OVERTIME 40
#define RATE1 0.15
#define RATE2 0.20
#define RATE3 0.25
#define WAGE 10.0
#define WAGE_OVERTIME 15.0
#define BREAK1 300.0
#define BREAK2 450.0
#define BASE1 (BREAK1 * RATE1)
#define BASE2 (BASE1 + ((BREAK2 - BREAK1) * RATE2))
int main(void) {
    int hr;
    double wage,income,tax;
    printf("Please enter the hr (q to quit) :");
    while ((scanf("%d",&hr)) == 1){
        if (hr <= WORK_OVERTIME)
        wage = hr * WAGE;
        else wage = WORK_OVERTIME * WAGE +((hr - WORK_OVERTIME) * WAGE_OVERTIME);
        if (wage <= BREAK1){
            tax = wage * RATE1;
        }
        else if (wage > 300 && wage <= 450 ){
            tax = BASE1 + (wage - BREAK1) * RATE2;
        }
        else tax = BASE2 + (wage - BREAK2) * RATE3;
        income = wage - tax;
        printf("The wage: %.2f income:%.2lf tax:%.2lf\n", wage, income, tax);
        printf("Please enter the hours (q to quit) :");
    }
    return 0;
}

8.
#include <stdio.h>
#define WORK_OVERTIME 40
#define RATE1 0.15
#define RATE2 0.20
#define RATE3 0.25
#define BREAK1 300.0
#define BREAK2 450.0
#define BASE1 (BREAK1 * RATE1)
#define BASE2 (BASE1 + ((BREAK2 - BREAK1) * RATE2))
int main(void) {
    int hr,number;
    double wage,income,tax,wage2;
    printf("------------------------------------------------------------------------\n");
    printf("Enter the number number corresponding to the desired pay rate or action:\n");
    printf("1) $8.15/hr                       2) $9.33/hr\n");
    printf("3) $10.00/hr                      4) $11.20/hr\n");
    printf("5) quit\n");
    printf("------------------------------------------------------------------------\n");
    printf("Please enter your choise:");
    while ((scanf("%d", &number)) == 1){
        switch (number){
            case 1: wage2 = 8.75;
                break;
            case 2: wage2 = 9.33;
                break;
            case 3: wage2 = 10.00;
                break;
            case 4: wage2 = 11.20;
                break;
            default:
                printf("Please enter the : 1 2 3 4 5 \n");
                printf("Please enter your choise:");
                continue; //continue使得程序跳过该循环的其余部分
        }
        if (number == 5) break;
        printf("Please enter the hours:");
        scanf("%d",&hr);
        if (hr <= WORK_OVERTIME)
        wage = hr * wage2;
        else wage = WORK_OVERTIME * wage2 +((hr - WORK_OVERTIME) * wage2 * 1.5);
        if (wage <= BREAK1){
            tax = wage * RATE1;
        }
        else if (wage > 300 && wage <= 450 ){
            tax = BASE1 + (wage - BREAK1) * RATE2;
        }
        else tax = BASE2 + (wage - BREAK2) * RATE3;
        income = wage - tax;
        printf("The wage: %.2f income:%.2lf tax:%.2lf\n", wage, income, tax);
        printf("------------------------------------------------------------------------\n");
        printf("Enter the number number corresponding to the desired pay rate or action:\n");
        printf("1) $8.15/hr                       2) $9.33/hr\n");
        printf("3) $10.00/hr                      4) $11.20/hr\n");
        printf("5) quit\n");
        printf("------------------------------------------------------------------------\n");
        printf("Please enter your choise:");
    }
    return 0;
}

9.
#include <stdio.h>
//写这题的时候我是懵逼的，只好看了下答案。2333
//解决方式是能被div整除的就不是素数
int main(void) {
    int limit;
    int num;
    int div;
    int numisprime; //当其为1的时候num为素数，如果num不是素数时，其变为0
    printf("Please enter a positive integer:");
    while ((scanf("%d", &limit)) == 1 && limit > 0) {
        if (limit > 1)
            printf("Here are the prime numbers up through %d\n", limit);
        else
            printf("No primes.\n");
        for (num = 2; num <= limit; num++)
        {
            for (numisprime = 1, div = 2; (div * div) <= num; div++)
                if (num % div == 0)
                    numisprime = 0;
            if (numisprime == 1)
                printf("%d is prime.\n", num);
        }
        printf("Please enter a positive integer (q to quit) :");
    }
    return 0;
}

10.
#include <stdio.h>
#define RATE1 0.15
#define RATE2 0.28
int main(void) {
    int number;
    double wage,tax,wage2; //wage工资，tax税收，wage2税金分界点
    printf("------------------------------------------------------------------------\n");
    printf("Enter the number number corresponding to the desired pay rate or action:\n");
    printf("1) Single tax                     2) Household tax\n");
    //1.单身 2.户主 3.共有 4.离异
    printf("3) Married Total tax              4) Married divorced tax\n");
    printf("5) quit\n");
    printf("------------------------------------------------------------------------\n");
    printf("Please enter your choise:");
    while ((scanf("%d", &number)) == 1 && number != 5){
        switch (number){
            case 1: wage2 = 17850; //单身
                break;
            case 2: wage2 = 23900; //户主
                break;
            case 3: wage2 = 29750; //已婚，共有
                break;
            case 4: wage2 = 14875; //已婚，离异
                break;
            default:
                printf("Please enter the : 1 2 3 4 5 \n");
                printf("Please enter your choise:");
                continue; //continue使得程序跳过该循环的其余部分
        }
        printf("Please enter the wage:");
        scanf("%lf",&wage);
        if (wage <= wage2)
            tax = wage *RATE1;
        else tax = wage2 * RATE1 + ((wage - wage2) * RATE2);
        printf("Your tax is :%.2lf\n", tax);
        printf("Please enter your choise:");
    }
    return 0;
}

11.
#include <stdio.h>
#define GOODS1 2.05  //货物1
#define GOODS2 1.15  //货物2
#define GOODS3 1.09  //货物3
#define BREAK1 5
#define BREAK2 20
#define BASE1 6.5
#define BASE2 14
#define DISCOUNT_MONEY 100
#define DISCOUNT 0.05
int main(void) {
    int number;
    double weight,cost,discount,cost2,goods;
    double all;
    double a,b,c,w_a,w_b,w_c;
    printf("请选择需要购买的货物:\n");
    printf("1)洋蓟:2.05/lb\n");
    printf("2)甜菜:1.15/lb\n");
    printf("3)胡萝卜:1.09/lb\n");
    printf("q)退出选购\n");
    printf("请输入你的选择:");
    while (scanf("%d", &number) == 1 ){
        switch (number){
            case 1:printf("请输入需要洋蓟的重量:");
                scanf("%lf", &a);
                break;
            case 2:printf("请输入需要甜菜的重量:");
                scanf("%lf", &b);
                break;
            case 3:printf("请输入需要胡萝卜的重量:");
                scanf("%lf", &c);
                break;
            default:printf("输入错误，请输入合适的选项(1,2,3,q):");
                continue;
        }
        w_a = w_a + a;
        w_b = w_b + b;
        w_c = w_c + c;
        a = b = c = 0;
        printf("请输入你的选择:");
    }
    cost = w_a * GOODS1 + w_b * GOODS2 + w_c * GOODS3;
    weight = w_a + w_b + w_c;
    if (cost >= DISCOUNT_MONEY){
        discount = cost * DISCOUNT;
        cost = cost * (1 - DISCOUNT);
    }
    if (weight <= BREAK1)
        cost2 = BASE1;
    else if (weight > BREAK1 && weight <= BREAK2)
        cost2 = BASE2;
    else cost2 = BASE2 + ((weight - BREAK2) * 0.5);
    printf("所需洋蓟的磅数:%.2lf\n", w_a);
    printf("所需甜菜的磅数:%.2lf\n", w_b);
    printf("所需胡萝卜的磅数:%.2lf\n", w_c);
    printf("订购的总磅数：%.2lf\n", weight);
    printf("所需洋蓟的费用:%.2lf\n", w_a * GOODS1);
    printf("所需甜菜的费用:%.2lf\n", w_b * GOODS2);
    printf("所需胡萝卜的费用:%.2lf\n", w_c * GOODS3);
    printf("订单的运输和装卸费用：%.2f\n", cost2);
    printf("订单的折扣：%.2f\n", discount);
    printf("订单的总费用（包括运输费用，而且还要减去折扣）:%.2f\n",cost + cost2);
    return 0;
}