c primer plus 第六版 第七章编程练习答案

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(编译环境 Microsoft Visual Studio 2019)

 

1.

[code]/*1.*/
#include<stdio.h>
int main(void)
{
char ch;
unsigned int s_count = 0;
unsigned int l_count = 0;
unsigned int o_count = 0;

printf("Please enter some text.(end with #)\n");
while ((ch = getchar()) != '#')
{
if (ch == ' ')
s_count++;
else if (ch == '\n')
l_count++;
else
o_count++;
}
printf("The number of spaces is %d\n", s_count);
printf("The number of newline characters is %d\n", l_count);
printf("The number of other characters is %d\n", o_count);

return 0;
}

 

 

2.

[code]/*2.*/
#include<stdio.h>
int main(void)
{
char ch;
unsigned int count = 0;

printf("Please enter some text.(end with #)\n");
while ((ch = getchar()) != '#')
{
if (ch == '\n')
continue;
printf("%4c-%-4hhu ",ch,ch);
count++;
if (count % 8 == 0)
putchar('\n');
}
printf("\n");

return 0;
}

 

 

3.

[code]/*3.*/
#include<stdio.h>
int main(void)
{
int integer;
unsigned int e_number = 0;
unsigned int o_number = 0;
unsigned int e_sum = 0;
unsigned int o_sum = 0;

printf("Please enter some integer.(0 to quit)\n");
scanf_s("%d", &integer);
while (integer != 0)
{
if (integer % 2 == 0)
{
e_number++;
e_sum += integer;
}
else
{
o_number++;
o_sum += integer;
}
scanf_s("%d", &integer);
}
if (e_number == 0)
printf("The even number is 0 and the average even number is 0\n");
else
printf("The even number is %u and the average even number is %.2f\n",
e_number, (float)e_sum / e_number);
if (o_number == 0)
printf("The odd number is 0 and the average odd number is 0\n");
else
printf("The odd number is %u and the average odd number is %.2f\n",
o_number, (float)o_sum / o_number);

return 0;
}

 

 

4.

[code]/*4.*/
#include<stdio.h>
int main(void)
{
char ch;
unsigned int count = 0;

printf("Please enter some text.(end with #)\n");
while ((ch = getchar()) != '#')
{
if (ch == '.')
{
ch = '!';
count++;
}
else if (ch == '!')
{
putchar(ch);
count++;
}
putchar(ch);
}
printf("\nA total of %u replacements.\n", count);

return 0;
}

 

 

5.

[code]/*5.*/
#include<stdio.h>
int main(void)
{
char ch;
unsigned int count = 0;

printf("Please enter some text.(end with #)\n");
while ((ch = getchar()) != '#')
{
switch (ch)
{
case '.':
ch = '!';
count++;
break;
case '!':
putchar(ch);
count++;
break;
default: break;
}
putchar(ch);
}
printf("\nA total of %u replacements.\n", count);

return 0;
}

 

 

6.

[code]/*6.*/
#include<stdio.h>
int main(void)
{
char ch;
char ch_pre = 0;
unsigned int count = 0;

printf("Please enter some text.\n");
while ((ch = getchar()) != '#')
{
if (ch == 'e')
ch_pre = ch;
if (ch_pre == 'e' && ch == 'i')
count++;
}
printf("The count of 'ei' is %u\n", count);

return 0;
}

 

 

7.

[code]
/*7.*/
#include<stdio.h>
#define BASE_PAY 10
#define BASE_TIME 40
#define OVER_PAY 15
#define TAX_1 300
#define TAX_2 150
#define TAX_1_RATE 0.15f
#define TAX_2_RATE 0.2f
#define TAX_OT_RATE 0.25f
int main(void)
{
unsigned int time;
float wage,tax;

printf("Please enter the number of hours you work a week.\n");
scanf_s("%u", &time);
if (time <= BASE_TIME)
wage = time * (float)BASE_PAY;
else
wage = BASE_TIME * (float)BASE_PAY + (time - BASE_TIME) * OVER_PAY;
if (wage < TAX_1)
tax = wage * TAX_1_RATE;
else if (wage < TAX_2)
tax = TAX_1 * TAX_1_RATE + (wage - TAX_1) * TAX_2_RATE;
else
tax = TAX_1 * TAX_1_RATE + TAX_2 * TAX_2_RATE + (wage - TAX_2) * TAX_OT_RATE;
printf("Total wage: %.2f\n", wage);
printf("Tax: %.2f\n", tax);
printf("Net income: %.2f\n", wage - tax);

return 0;
}

 

 

8.

[code]/*8.*/
#include<stdio.h>
#define BASE_TIME 40
#define OVER_PAY 15
#define TAX_1 300
#define TAX_2 150
#define TAX_1_RATE 0.15f
#define TAX_2_RATE 0.2f
#define TAX_OT_RATE 0.25f
float level(void);
void star(void);
int main(void)
{
unsigned int time;
float wage, tax, salary;

while(1)
{
if ((salary = level()) == 0)
break;
printf("Please enter the number of hours you work a week.\n");
scanf_s("%u", &time);
if (time <= BASE_TIME)
wage = time * (float)salary;
else
wage = BASE_TIME * (float)salary + (time - BASE_TIME) * OVER_PAY;
if (wage < TAX_1)
tax = wage * TAX_1_RATE;
else if (wage < TAX_2)
tax = TAX_1 * TAX_1_RATE + (wage - TAX_1) * TAX_2_RATE;
else
tax = TAX_1 * TAX_1_RATE + TAX_2 * TAX_2_RATE + (wage - TAX_2) * TAX_OT_RATE;
printf("Total wage: %.2f\n", wage);
printf("Tax: %.2f\n", tax);
printf("Net income: %.2f\n", wage - tax);
}

return 0;
}

float level(void)
{
const float level_1 = 8.75f;
const float level_2 = 9.33f;
const float level_3 = 10.00f;
const float level_4 = 11.20f;
float salary;
int flag;
_Bool cycle;

do
{
cycle=0;

3ff7
star();
printf("\nEnter the number corresponding to the desired pay rate or action.\n\n");
printf("1) $8.75/hr\t\t2) $9.33/hr\n\n");
printf("3) $10.00/hr\t\t4) $11.20/hr\n\n");
printf("5) quit\n\n");
star();
printf("Your choice: ");
scanf_s("%d", &flag);
switch (flag)
{
case 1: salary = level_1; break;
case 2: salary = level_2; break;
case 3: salary = level_3; break;
case 4: salary = level_4; break;
case 5: salary = 0; printf("bye\n"); break;
default:
printf("Please enter right number.\n");
cycle = 1;
break;
}
}while(cycle==1);

return salary;
}

void star(void)
{
printf("********************************************************************\n");
}

 

 

9.

[code]/*9.*/
#include<stdio.h>
int main(void)
{
unsigned int value, per, i;
_Bool prime;

printf("Please enter a positive integer: ");
scanf_s("%u", &value);
printf("Prime number:\n");
for (per = 2; per <= value; per++)
{
for (prime = 1, i = 2; i * i <= per; i++)
{
if (per % i == 0)
prime = 0;
}
if (prime == 1)
printf("%u ", per);
}
putchar('\n');

return 0;
}

 

 

10.

[code]/*10.*/
#include<stdio.h>
#define TAX_S 17580
#define TAX_H 23900
#define TAX_MC 29750
#define TAX_MD 14875
#define TAX_RATE_B 0.15f
#define TAX_RATE_O 0.28f
void star(void);
int main(void)
{
unsigned short type;
unsigned int tax_base;
float income, tax;
_Bool flag = 1;
_Bool re;

do
{
do
{
re = 0;
printf("*******************************\n");
printf("Please choose your tax type.\n");
printf("1. single\n2. householder\n");
printf("3. married,common\n4. married,divorced\n");
printf("5. quit\n\n");
printf("Your choice: ");
scanf_s("%hu", &type);
switch (type)
{
case 1: tax_base = TAX_S; break;
case 2: tax_base = TAX_H; break;
case 3: tax_base = TAX_MC; break;
case 4: tax_base = TAX_MD; break;
case 5: flag = 0; printf("bye"); break;
default:
printf("\nPlease enter right number.\n");
re = 1;
break;
}
} while (re);
if (flag)
{
printf("Please enter your income: ");
scanf_s("%f", &income);
if (income <= tax_base)
tax = income * TAX_RATE_B;
else
tax = tax_base * TAX_RATE_B + (income - tax_base) * TAX_RATE_O;
printf("Your tax is %.2f\n\n", tax);
}
} while (flag);
putchar('\n');

return 0;
}

 

 

11.

[code]/*11.*/
#include<stdio.h>
#define ARTICHOKE 2.05f
#define BEET 1.15f
#define CARROT 1.09f
#define DISCOUNT_M 100
#define DISCOUNT_R 0.05
#define FARE_P_1 5
#define FARE_P_2 20
#define FARE_1 6.5
#define FARE_2 14
#define FARE_OT 0.5
int main(void)
{
char goods, ch;
float a_pound = 0;
float b_pound = 0;
float c_pound = 0;
float pound, total_pound;
float fare, total_cost;
float discount = 0;
float a_cost, b_cost, c_cost;
_Bool re;

do
{
re = 0;
printf("*****************************************\n");
printf("Please select the goods you need.\n");
printf("a. artichoke\nb. beet\nc. carrot\n\n");
printf("Your choice: ");
goods = getchar();//输入时会把回车的换行符放在缓冲区中，下一次getchar()或scanf(%c)会读取到换行符
getchar();//所以每次输入字符时候都要用一个getchar()将换行符读取掉
switch (goods)
{
case 'a':
printf("Artichoke weight(pound): ");
scanf_s("%f", &pound); getchar();
a_pound += pound;
break;
case 'b':
printf("Beet weight(pound): ");
scanf_s("%f", &pound); getchar();
b_pound += pound;
break;
case 'c':
printf("Carrot weight(pound): ");
scanf_s("%f", &pound); getchar();
c_pound += pound;
break;
default:
printf("\nPlease enter the correct letter.\n");
re = 1; break;
}
if (re != 1)
{
printf("\nDo you want to select another goods?\n");
printf("Y.yes\t\tN.no\n");
while ((ch = getchar()) != 'Y' && ch != 'N')
{
getchar();
printf("Please enter correct letter.\n");
}
if (ch == 'Y')
{
getchar();
re = 1;
}
else
printf("\nThank you for purchase.\n\n");
}
} while (re == 1);

a_cost = a_pound * ARTICHOKE;
b_cost = b_pound * BEET;
c_cost = c_pound * CARROT;
total_cost = a_cost + b_cost + c_cost;
total_pound = a_pound + b_pound + c_pound;
if (total_cost >= DISCOUNT_M)
discount = DISCOUNT_M * DISCOUNT_R;
if (total_pound <= 5)
fare = 6.5f;
else if (total_pound <= 20)
fare = 14.0f;
else
fare = 14.0f + (total_pound - 14) * 0.5f;

printf("%30s  %15s  %15s  %15s\n","Goods:","Artichoke","Beet","Carrot");
printf("%30s  %15s  %15s  %15s\n","Price(/pound):","2.05","1.15","1.09");
printf("%30s  %15.2f  %15.2f  %15.2f\n",
"Ordered weight(pound):",a_pound, b_pound, c_pound);
printf("%30s  %15.2f  %15.2f  %15.2f\n",
"Cost:",a_cost, b_cost, c_cost);
printf("%30s  %.2f\n", "Total cost:", total_cost);
printf("%30s  %.2f\n", "Discount:", discount);
printf("%30s  %.2f\n", "Freight and packing charges:", fare);
printf("%30s  %.2f\n", "Total payment:",total_cost - discount + fare);

return 0;
}