⑤ Exercises, Programming Projects

K. N. King C Programming - Chapter 5. Exercises, Programming Projects

[Week 4] Hacking Cat’s Weekly Study

Exercises

Section 5.1 (1)

1. The following program fragments illustrate the relational and equality operators. Show the output produced by each, assuming that i, j. and k are int variables.

1번 문제는 연산자의 결합순서, 우선순위에 관한 문제입니다.
- https://blog.naver.com/huffman_/222974844309

(a) i * j 의 연산 결과는 6이다. 따라서, i * j == 6 연산 시에는 참(1) 결과 값을 반환합니다.

# soneg@soneg: ~/hackingcats/5/exercises                                              (17:27:18)
ζ cat 1.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i = 2; j = 3;
 
        k = i * j == 6;
        printf("%d", k);
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:27:19)
ζ ./1
1%

(b) <, > 는 결합 방향이 → 이므로 (k > i) < j 순서로 연산이 진행됩니다.
- 따라서, "(1 > 5) < 10" → "0 < 10" → 1 결과적으로 1이 반환됩니다.

# soneg@soneg: ~/hackingcats/5/exercises                                              (17:30:48)
ζ cat b.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i= 5; j= 10; k=1;
 
        printf("%d", k > i < j);
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:30:51)
ζ gcc -o b b.c
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:30:54)
ζ ./b
1%

# soneg@soneg: ~/hackingcats/5/exercises                                              (17:36:53)
ζ cat c.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i= 3; j= 2; k=1;
 
        printf("%d", i < j == i < k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:36:55)
ζ gcc -o c c.c
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:36:59)
ζ ./c
1%

(d) i % j + 1 이 먼저 계산되고 4 < 5 연산이 수행되므로 참(1) 값을 반환합니다.

# soneg@soneg: ~/hackingcats/5/exercises                                              (17:40:37)
ζ cat d.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=3; j=4; k=5;
 
        printf("%d", i % j + 1 < k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:40:39)
ζ gcc -o d d.c
# soneg@soneg: ~/hackingcats/5/exercises                                              (17:40:42)
ζ ./d
1%

Section 5.1 (2)

1. The following program fragments illustrate the logical operators. Show the output produced by each, assuming that i, j, and k are int variables.

(a) C언어에서는 0이 아닌 정수는 모두 참으로 판단한다. 논리 부정 연산자 ! 가 정수 값 앞에 오면 그 반대의 값을 반환하므로 거짓(0) 값을 반환하게 된다. 따라서 0 < 5 의 연산 결과는 참이므로 1 값을 반환한다.

# soneg@soneg: ~/hackingcats/5/exercises/2                                               (17:45:17)
ζ cat a.c
#include <stdio.h>
 
int main()
{
        int i, j;
        i=10; j=5;
 
        printf("%d", !i < j);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (17:45:18)
ζ gcc -o a a.c
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (17:45:20)
ζ ./a
1%

(b) 이전 문제와 동일하다. 변수 i에 논리 부정 연산이 2번 계산되면 거짓이 되었다가 다시 참이 된다. 변수 j의 논리 부정 연산 결과는 0이므로 1 + 0 이 계산되어 1 을 반환한다.

# soneg@soneg: ~/hackingcats/5/exercises/2                                               (17:46:38)
ζ cat b.c
#include <stdio.h>
 
int main()
{
        int i, j;
        i=2; j=1;
 
        printf("%d", !!i + !j);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (17:46:39)
ζ ./b
1%

# soneg@soneg: ~/hackingcats/5/exercises/2                                               (19:44:17)
ζ cat c.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=5; j=0, k=-5;
 
        printf("%d", i && j || k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (19:44:19)
ζ gcc -o c c.c
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (19:44:22)
ζ ./c
1

(d) 1 < 2 는 참을 반환하고 1 || 3 또한 참을 반환하므로 1이 출력된다.

# soneg@soneg: ~/hackingcats/5/exercises/2                                               (19:49:33)
ζ cat d.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=1; j=2, k=3;
 
        printf("%d", i < j || k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (19:49:35)
ζ gcc -o d d.c
# soneg@soneg: ~/hackingcats/5/exercises/2                                               (19:49:38)
ζ ./d
1%

Section 5.1 (3)

1. The following program fragments illustrate the short-circuit behavior of logical expressions. Show the output produced by each, assuming that i, j. and k are int variables.

(a) ++j 가 계산되어 변수 j 의 값은 5로 변경된다. 이후 i < j, j < k 연산이 순차적으로 진행된다. 최종적으로 1 || 0 이 계산되며 OR 연산에 따라 참(1) 값이 출력된다.

# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:51:37)
ζ cat a.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=3; j=4, k=5;
 
        printf("%d", i < j || ++j < k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:51:37)
ζ gcc -o a a.c
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:51:42)
ζ ./a
1

(b) 7 - 7 && 7++ < 9 연산은 0 && 1 연산과 동일하다. 따라서 첫 번째 프린트 문에서는 0을 반환한다. 이후 i, j, k 값은 초기 설정 값과 동일하다.

# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:54:38)
ζ cat b.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=7; j=8, k=9;
 
        printf("%d ", i - 7 && j++ < k);
        printf("%d, %d, %d", i, j, k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:54:39)
ζ gcc -o b b.c
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:54:42)
ζ ./b
0 7, 8, 9%

(c) 첫 번째 프린트 문에 의해 i = 8 로 설정된다. 이 때, OR 연산에서 좌측의 연산 결과가 참이기 때문에 우측 연산(j=k)는 무시된다. 따라서, i, j, k의 값은 8, 8, 9 로 설정된다.

# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:59:08)
ζ cat c.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=7; j=8, k=9;
 
        printf("%d ", (i = j) || (j = k));
        printf("%d, %d, %d", i, j, k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:59:09)
ζ gcc -o c c.c
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (19:59:11)
ζ ./c
1 8, 8, 9%

(d) 이전 문제와 동일하게 ++i 의 연산 결과가 참이므로, || 우측의 연산은 진행되지 않는다.
- 따라서, i, j, k 의 최종 값은 2, 1 1 가 된다.

# soneg@soneg: ~/hackingcats/5/exercises/3                                               (20:03:27)
ζ cat d.c
#include <stdio.h>
 
int main()
{
        int i, j, k;
        i=1; j=1, k=1;
 
        printf("%d ", ++i || ++j && ++k);
        printf("%d, %d, %d", i, j, k);
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (20:03:30)
ζ gcc -o d d.c
# soneg@soneg: ~/hackingcats/5/exercises/3                                               (20:03:34)
ζ ./d
1 2, 1, 1

Section 5.1. (4)

1. Write a single expression whose value is either-1.0, or +1. depending on whether i is less than, equal to, or greater than j. respectively.

# soneg@soneg: ~/hackingcats/5/exercises/4                                                 (20:20:31)
ζ cat 4.c
#include <stdio.h>
 
int main(void)
{
        int i, j;
 
        printf("Enter value of i: ");
        scanf("%d", &i);
        printf("Enter value of j: ");
        scanf("%d", &j);
 
        if (i < j)
        {
                printf("-1.0");
        } else if (i == j)
        {
                printf("0");
        } else {
                printf("+1.0");
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises/4                                                 (20:20:32)
ζ gcc -o 4 4.c
# soneg@soneg: ~/hackingcats/5/exercises/4                                                 (20:20:34)
ζ ./4
Enter value of i: 1
Enter value of j: 2
-1.0%

Section 5.2. (5)

조건문을 위와 같이 설정했을 경우, n 값이 1 이상인지 먼저 확인하여 참 혹은 거짓 값을 반환한다.
n 값이 0 이라면 n >= 1 결과가 거짓이므로 두번째 연산 ((n >= 1) <= 10)은 수행되지 않는다.
- 따라서 0 이 반환된다.

# soneg@soneg: ~/hackingcats/5/exercises                                                   (20:28:45)
ζ cat 5.c
#include <stdio.h>
 
int main(void)
{
        int n = 0;
 
        if (n >= 1 <= 10)
        {
                printf("%d", n);
        }
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                                   (20:28:48)
ζ gcc -o 5 5.c
# soneg@soneg: ~/hackingcats/5/exercises                                                   (20:28:50)
ζ ./5
0%

Section 5.2. (6)

n == -9 는 참이 아니므로 아무런 값도 출력되지 않는다.

# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:33:11)
ζ cat 6.c
#include <stdio.h>
 
int main(void)
{
        int n = 5;
 
        if (n == 1-10)
        {
                printf("n is between 1 and 10\n");
        }
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:33:12)
ζ gcc -o 6 6.c
./%                                                                                                              # soneg@soneg: ~/hackingcats/5/exercises                                                             (20:33:16)
ζ ./6
# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:33:23)
ζ

Section 5.2. (7)

i >= 0는 참이므로 17을 출력한다.

# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:37:51)
ζ cat 7.c
#include <stdio.h>
 
int main(void)
{
        int i = 17;
 
        printf("%d\n", i >= 0 ? i : -i);
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:37:52)
ζ gcc -o 7 7.c
.%                                                                                                               # soneg@soneg: ~/hackingcats/5/exercises                                                             (20:37:56)
ζ ./7
17

Section 5.2. (8)

19살 이상인지 미만인지만 확인하면 된다. 삼항연산자를 사용하여 표현식을 작성했다.

# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:42:49)
ζ cat 8.c
#include <stdio.h>
#include <stdbool.h>
 
int main(void)
{
        int age;
        printf("Enter your age:");
        scanf("%d", &age);
 
        if (age >= 19 ? true : false) {
                printf("You are adult.");
        } else {
                printf("You are teenager.");
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:42:50)
ζ gcc -o 8 8.c
# soneg@soneg: ~/hackingcats/5/exercises                                                             (20:42:51)
ζ ./8
Enter your age:80
You are adult.

Section 5.2 (9)

동일하다.

Section 5.3 (10)

onettwo 가 출력된다. (case 문에 종료 구문이 존재하지 않아 순차적으로 모두 출력된다.)

Section 5.3 (11)

# soneg@soneg: ~/hackingcats/5/exercises                                                             (21:09:03)
ζ cat 11.c
#include <stdio.h>
#include <stdbool.h>
 
int main(void)
{
        int area_code;
        printf("Enter your area code: ");
        scanf("%d", &area_code);
 
        switch (area_code) {
                case 229: printf("Albany"); break;
                case 404: printf("Atlanta"); break;
                case 470: printf("Atlanta"); break;
                case 478: printf("Macon"); break;
                case 678: printf("Atlanta"); break;
                case 706: printf("Columbus"); break;
                case 762: printf("Columbus"); break;
                case 770: printf("Atlanta"); break;
                case 912: printf("Savannah"); break;
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/exercises                                                             (21:09:06)
ζ gcc -o 11 11.c
# soneg@soneg: ~/hackingcats/5/exercises                                                             (21:09:08)
ζ ./11
Enter your area code: 404
Atlanta%

Programming Projects

PP (1)

# soneg@soneg: ~/hackingcats/5/projects                                                              (21:13:16)
ζ cat 1.c
#include <stdio.h>
 
int main(void) {
        int number;
 
        printf("Enter a number: ");
        scanf("%d", &number);
 
        if ((number / 100) > 0) {
                printf("The number %d has %d digits", number, (number / 100));
        } else if ((number / 10) > 0) {
                printf("The number %d has %d digits", number, (number / 10));
        } else {
                printf("The number %d has 1 digits", number);
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:13:18)
ζ gcc -o 1 1.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:13:21)
ζ ./1
Enter a number: 23
The number 23 has 2 digits%

PP (2)

# soneg@soneg: ~/hackingcats/5/projects                                                              (21:19:36)
ζ cat 2.c
#include <stdio.h>
 
int main(void) {
        int hour, minute;
 
        printf("Enter a 24-hour time: ");
        scanf("%d:%d", &hour, &minute);
 
        if ((hour / 12) == 1) {
                printf("Equivalent 12-hour time: %d:%d PM", hour, minute);
        } else if ((hour / 12) > 1) {
                printf("Equivalent 12-hour time: %d:%d PM", (hour % 12), minute);
        } else {
                printf("Equivalent 12-hour time: %d:%d AM", hour, minute);
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:19:37)
ζ gcc -o 2 2.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:19:39)
ζ ./2
Enter a 24-hour time: 12:45
Equivalent 12-hour time: 12:45 PM%

PP (3)

생략

PP (4)

ζ cat 4.c
#include <stdio.h>
 
int main(void)
{
        int knots;
 
        printf("Enter value of wind speed (in knots): ");
        scanf("%d", &knots);
 
        if (knots < 1) {
                printf("Description: Calm");
        } else if (knots <= 3) {
                printf("Description: Light air");
        } else if (knots <= 27) {
                printf("Description: Breeze");
        } else if (knots <= 47) {
                printf("Description: Gale");
        } else if (knots <= 63) {
                printf("Description: Storm");
        } else {
                printf("Description: Hurricane");
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:34:44)
ζ gcc -o 4 4.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:34:47)
ζ ./4
Enter value of wind speed (in knots): 35
Description: Gale%

PP (5)

# soneg@soneg: ~/hackingcats/5/projects                                                              (21:46:52)
ζ cat 5.c
#include <stdio.h>
 
int main(void)
{
        int income;
 
        printf("Enter value of your income: ");
        scanf("%d", &income);
 
        if (income < 750) {
                printf("Amount of tax: 1 percent of income");
        } else if (income <= 2250) {
                printf("Amount of tax: $7.50 plus 2 percent of income");
        } else if (income <= 3750) {
                printf("Amount of tax: $37.50 plus 3 percent of income");
        } else if (income <= 5250) {
                printf("Amount of tax: $82.50 plus 4 percent of income");
        } else if (income <= 7000) {
                printf("Amount of tax: $142.50 plus 5 percent of income");
        } else {
                printf("Amount of tax: $230.00 plus 6 percent of income");
        }
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:46:53)
ζ gcc -o 5 5.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:46:55)
ζ ./5
Enter value of your income: 6666
Amount of tax: $142.50 plus 5 percent of income%

PP (6)

생략

PP (7)

# soneg@soneg: ~/hackingcats/5/projects                                                              (21:51:06)
ζ cat 7.c
#include <stdio.h>
 
int main(void)
{
        int a, b, c, d;
        int largest, smallest;
 
        printf("Enter four integers: ");
        scanf("%d %d %d %d", &a, &b, &c, &d);
 
        largest = a; smallest = b;
 
        if (largest < b) {
                largest = b;
        } else if (largest < c) {
                largest = c;
        } else if (largest < d) {
                largest = d;
        }
 
        if (smallest > b) {
                smallest = b;
        } else if (smallest > c) {
                smallest = c;
        } else if (smallest > d) {
                smallest = d;
        }
 
        printf("Largest: %d\n", largest);
        printf("Smallest: %d\n", smallest);
 
        return 0;
 
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:51:08)
ζ gcc -o 7 7.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (21:51:09)
ζ ./7
Enter four integers: 21 43 10 35
Largest: 43
Smallest: 10

PP (8)

생략

PP (9)

# soneg@soneg: ~/hackingcats/5/projects                                                              (22:11:20)
ζ cat 9.c
#include <stdio.h>
 
int main(void) {
        int yy1, yy2, mm1, mm2, dd1, dd2;
        int days1, days2;
 
        printf("Enter first date (mm/dd/yy): ");
        scanf("%d/%d/%d", &dd1, &mm1, &yy1);
 
        printf("Enter second date (mm/dd/yy): ");
        scanf("%d/%d/%d", &dd2, &mm2, &yy2);
 
        days1 = 365 * yy1 + 30 * mm1 + dd1;
        days2 = 365 * yy2 + 30 * mm2 + dd2;
 
        if (days1 < days2) {
                printf("%d/%d/%02d is earlier than %d/%d/%02d", dd1, mm1, yy1, dd2, mm2, yy2);
        } else {
                printf("%d/%d/%02d is earlier than %d/%d/%02d", dd2, mm2, yy2, dd1, mm1, yy1);
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (22:11:22)
ζ ./9
Enter first date (mm/dd/yy): 3/6/08
Enter second date (mm/dd/yy): 5/17/07
5/17/07 is earlier than 3/6/08%

PP (10)

# soneg@soneg: ~/hackingcats/5/projects                                                              (22:15:47)
ζ cat 10.c
#include <stdio.h>
 
int main(void)
{
        int score;
        printf("Enter numeric grade: ");
        scanf("%d", &score);
 
        switch (score / 10) {
                case 9: printf("Letter grade: A"); break;
                case 8: printf("Letter grade: B"); break;
                case 7: printf("Letter grade: C"); break;
                case 6: printf("Letter grade: D"); break;
                default: printf("Letter grade: F");
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (22:15:49)
ζ gcc -o 10 10.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (22:15:50)
ζ ./10
Enter numeric grade: 84
Letter grade: B%

PP (11)

# soneg@soneg: ~/hackingcats/5/projects                                                              (22:20:48)
ζ cat 11.c
#include <stdio.h>
 
int main(void)
{
        int number;
 
        printf("Enter a two-digit number: ");
        scanf("%d", &number);
 
        switch (number / 10) {
                case 1: printf("ten-"); break;
                case 2: printf("twenty-"); break;
                case 3: printf("thirty-"); break;
                case 4: printf("fourty-"); break;
                case 5: printf("fifty-"); break;
                case 6: printf("sixsty-"); break;
                case 7: printf("seventy-"); break;
                case 8: printf("eighty-"); break;
                case 9: printf("ninety-"); break;
        }
 
        switch (number % 10) {
                case 1: printf("one"); break;
                case 2: printf("two"); break;
                case 3: printf("three"); break;
                case 4: printf("four"); break;
                case 5: printf("five"); break;
                case 6: printf("six"); break;
                case 7: printf("seven"); break;
                case 8: printf("eight"); break;
                case 9: printf("nine"); break;
        }
 
        return 0;
}
# soneg@soneg: ~/hackingcats/5/projects                                                              (22:20:50)
ζ gcc -o 11 11.c
# soneg@soneg: ~/hackingcats/5/projects                                                              (22:20:53)
ζ ./11
Enter a two-digit number: 45
fourty-five%

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ikiw genos

Explorer

⑤ Exercises, Programming Projects

Exercises

Section 5.1 (1)

Section 5.1 (2)

Section 5.1 (3)

Section 5.1. (4)

Section 5.2. (5)

Section 5.2. (6)

Section 5.2. (7)

Section 5.2. (8)

Section 5.2 (9)

Section 5.3 (10)

Section 5.3 (11)

Programming Projects

PP (1)

PP (2)

PP (3)

PP (4)

PP (5)

PP (6)

PP (7)

PP (8)

PP (9)

PP (10)

PP (11)

Graph View

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