[C++知识库] C语言程序设计：现代方法第5章课后习题答案

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[C++知识库]C语言程序设计：现代方法第5章课后习题答案

除书籍作者给出的题解外，其余为个人所解，仅供参考

第5章选择语句

练习题

(a) 1
(b) 1
(c) 1
(d) 0
(a) 1
(b) 1
(c) 1
(d) 1
(a) 1; 3 4 5
(b) 0; 7 8 9
(c) 1; 8 8 9
(d) 1; 2 1 1
(i > j) - (i < j)
合法，条件恒成立打印输出
合法，条件不成立什么也不做
结果相同皆为17

 if (age >= 13 && age <= 19)
     teenager = true;
 else
     teenager = false;

等价
onetwo

switch (area_code) {
    case 229: printf("Albany"); break;
    case 404: case 470: case 678: case 770:
        printf("Atlanta"); break;
    case 478: printf("Macon"); break;
    case 706: case 762:
        printf("Columbus"); break;
    case 912: printf("Savannah"); break;
    default: printf("Area code not recognized"); break;
}

编程题

 int num;
 printf("Enter a number: ");
 scanf("%d", &num);
 if (num >= 0 && num <= 9)
     printf("The number %d has 1 digits\n", num);
 else if (num >= 10 && num <= 99)
     printf("The number %d has 2 digits\n", num);
 else if (num >= 100 && num <= 999)
     printf("The number %d has 3 digits\n", num);
 else
     printf("The number %d has 4 digits\n", num);

 int hours, minutes;

 printf("Enter a 24-hour time: ");
 scanf("%d:%d", &hours, &minutes);

 printf("Equivalent 12-hour time: ");
 if (hours == 0)
     printf("12:%.2d AM\n", minutes);
 else if (hours < 12)
     printf("%d:%.2d AM\n", hours, minutes);
 else if (hours == 12)
     printf("%d:%.2d PM\n", hours, minutes);
 else
     printf("%d:%.2d PM\n", hours - 12, minutes);

 int mount, commission, competitor_commission;
 float price, value;
 printf("Enter price and mount: ");
 scanf("%d%d", &price, &mount);

 if (mount < 2000)
     competitor_commission = 33.3f * mount;
 else
     competitor_commission = 33.2f * mount;

 value = price * mount;
 if (value < 2500.f)
     commission = 30.00f + .017f * value;
 else if (value < 6250.00f)
     commission = 56.00f + .0066f * value;
 else if (value < 20000.00f)
     commission = 76.00f + .0034f * value;
 else if (value < 50000.00f)
     commission = 100.00f + .0022f * value;
 else if (value < 500000.00f)
     commission = 155.00f + .0011f * value;
 else
     commission = 255.00f + .0009f * value;

 if (commission < 39)
     commission = 39.00f;

 printf("Commission: $%.2f\n", commission);
 printf("Commission of competitor: $%.2f\n", competitor_commission);

 int speed;
 printf("Enter wind speed: ");
 scanf("%f", &speed);

 if (speed < 1)
     printf("Calm");
 else if (speed >= 1 && speed <= 3)
     printf("Light air\n");
 else if (speed >= 4 && speed <= 27)
     printf("Breeze\n");
 else if (speed >= 28 && speed <= 47)
     printf("Gale\n");
 else if (speed >= 48 && speed <= 63)
     printf("Storm\n");
 else
     printf("Hurricane\n");

 float value, taxi;
 printf("Enter your value of income: ");
 scanf("%d", &value);

 if (value <= 750)
     taxi = value * 0.01f;
 else if (value <= 2250)
     taxi = (value - 750) * 0.02f + 7.5f;
 else if (value <= 3750)
     taxi = (value - 2250) * 0.03f + 37.5f;
 else if (value <= 5250)
     taxi = (value - 3750) * 0.04f + 82.5f;
 else if (value <= 7000)
     taxi = (value - 5250) * 0.05f + 142.5f;
 else
     taxi = (value - 7000) * 0.06f + 230.0f;

 printf("Your taxi: %d\n", taxi);

 int check_digit, d, i1, i2, i3, i4, i5, j1, j2, j3, j4, j5,
 first_sum, second_sum, total;

 printf("Enter the first (single) digit: ");
 scanf("%1d", &d);
 printf("Enter first group of five digits: ");
 scanf("%1d%1d%1d%1d%1d", &i1, &i2, &i3, &i4, &i5);
 printf("Enter second group of five digits: ");
 scanf("%1d%1d%1d%1d%1d", &j1, &j2, &j3, &j4, &j5);
 printf("Enter the last (single) digit: ");
 scanf("%1d", &check_digit);

 first_sum = d + i2 + i4 + j1 + j3 + j5;
 second_sum = i1 + i3 + i5 + j2 + j4;
 total = 3 * first_sum + second_sum;

 if (check_digit == 9 - ((total - 1) % 10))
     printf("VALID\n");
 else
     printf("NOT VALID\n");

 int a, b, c, d;
 int min1, min2, max1, max2;

 printf("Enter four integers: ");
 scanf("%d%d%d%d", &a, &b, &c, &d);

 if (a < b) min1 = a, max1 = b;
 else min1 = b, max1 = a;

 if (c < d) min2 = c, max2 = d;
 else min2 = d, max2 = c;

 if (min1 > min2) min1 = min2;
 if (max1 < max2) max1 = max2;

 printf("Largest: %d\n", max1);
 printf("Smallest: %d", min1);

 int hours, minutes;
 printf("Enter a 24-hours time: ");
 scanf("%d:%d", &hours, &minutes);

 int time = hours * 60 + minutes;
 if (time < 480 || time >= 1140)
     printf("Cloest departure time is 8:00 a.m., arriving at 10:16 a.m.\n");
 else if (time < 583)
     printf("Closest departure time is 9:43 a.m., arriving at 11:52 a.m.");
 else if (time < 679)
     printf("Closest departure time is 11:19 a.m., arriving at 1:31 p.m");
 else if (time < 767)
     printf("Closest departure time is 12:47 a.m., arriving at 3:00 p.m");
 else if (time < 840)
     printf("Closest departure time is 2:00 p.m., arriving at 4:08 p.m.");
 else if (time < 945)
     printf("Closest departure time is 3:45 p.m., arriving at 5:55 p.m.");
 else if ()
     printf("Closest departure time is 7:00 p.m., arriving at 9:20 p.m.");
 else
     printf("Closest departure time is 9:45 p.m., arriving at 11:58 p.m.");

 int month, day, year, early_month = 0, early_day = 0, early_year = 0;

 printf("Enter a date (mm/dd/yy): ");
 scanf("%d/%d/%d", &early_month, &early_day, &early_year);
 printf("Enter a date (mm/dd/yy): ");
 scanf("%d/%d/%d", &month, &day, &year);

 if (year < early_year) {
         early_month = month;
         early_day = day;
         early_year = year;
     } else if (year == early_year && month < early_month) {
         early_month = month;
         early_day = day;
         early_year = year;
     } else if (year == early_year && month == early_month && day < early_day) {
         early_month = month;
         early_day = day;
         early_year = year;
     }

 printf("%d/%.2d/%.2d is the earliest date\n", early_month, early_day, early_year);

int grade;

printf("Enter numerical grade: ");
scanf("%d", &grade);

if (grade < 0 || grade > 100) {
    printf("Illegal grade\n");
    return 0;
}

switch (grade/10) {
    case 10: case 9: printf("A\n"); break;
    case 8: printf("B\n"); break;
    case 7: printf("C\n"); break;
    case 6: printf("D\n"); break;
    case 5: case 4: case 3: case 2: case 1: case 0:
        printf("F\n"); break;
}

int m, n;

printf("Enter a two-digit number: ");
scanf("%1d%1d", &m, &n);
printf("Your entered the number ");
switch (m) {
    case 1:
        switch (n) {
            case 0: printf("ten\n"); break;
            case 1: printf("eleven\n"); break;
            case 2: printf("twelve\n"); break;
            case 3: printf("thirteen\n"); break;
            case 4: printf("fourteen\n"); break;
            case 5: printf("fifteen\n"); break;
            case 6: printf("sixteen\n"); break;
            case 7: printf("seventeen\n"); break;
            case 8: printf("eighteen\n"); break;
            case 9: printf("nineteen\n"); break;
        }
        return 0;
    case 2: printf("twenty"); break;
    case 3: printf("thirty"); break;
    case 4: printf("forty"); break;
    case 5: printf("fifty"); break;
    case 6: printf("sixty"); break;
    case 7: printf("seventy"); break;
    case 8: printf("eighty"); break;
    case 9: printf("ninety"); break;
}
switch (n) {
    case 0: break;
    case 1: printf("-one\n"); break;
    case 2: printf("-two\n"); break;
    case 3: printf("-three\n"); break;
    case 4: printf("-four\n"); break;
    case 5: printf("-five\n"); break;
    case 6: printf("-six\n"); break;
    case 7: printf("-seven\n"); break;
    case 8: printf("-eight\n"); break;
    case 9: printf("-nine\n"); break;
}