[C] C언어 for Beginner 4판 응용 문제, 결과 추측하기

#define _CRT_SECURE_NO_WARNINGS
 
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <time.h>
#include <string.h>
 
char* upper_lower(char* s) {
    int i;
    int diff = 'a' - 'A';
 
    for (i = 0; i < strlen(s); i++) {
        if (s[i] >= 'A' && s[i] <= 'Z') s[i] += diff;
        else if (*(s + i) >= 'a' && *(s + i) <= 'z') *(s + i) -= diff;
    }
 
    return s;
}
 
int getLotto() {
    return rand() % 45 + 1;
}
 
char* upper_lower_re(char* s) {
    int i;
    int diff = 'a' - 'A';
 
    for (i = 0; i < strlen(s); i++) {
        if (*(s + i) >= 'A' && *(s + i) <= 'Z') *(s + i) += diff;
        else if (s[i] >= 'a' && s[i] <= 'z') s[i] -= diff;
    }
 
    return s;
}
 
int throwDice() {
    return rand() % 6 + 1;
}
 
void main() {
    // C언어 for beginner 4판 연습문제 기본 + 응용 풀이
    // 08-예제모음22) 
    int i, k;
    int gugu[8][9];
 
    for (i = 2; i < 10; i++) {
        printf("#제%d단#  ", i);
    }
    printf("\n");
 
    for (i = 0; i < 9; i++) {
        for (k = 0; k < 8; k++) {
            gugu[k][i] = (i + 1) * (k + 2);
            printf("%dX%d= %2d  ", k + 2, i + 1, gugu[k][i]);
        }
        printf("\n");
    }
    printf("\n");
 
 
    // 08-예제모음22) 
    int i, k;
    int gugu[8][9];
 
    FILE* wfp;
    wfp = fopen("c:\\cookc\\gugu0618.txt", "w");
 
    for (i = 2; i < 10; i++) {
        printf("#제%d단# ", i);
        fprintf(wfp, "#제%d단# ", i);
    }
    printf("\n");
    fprintf(wfp, "\n");
 
    for (i = 0; i < 9; i++) {
        for (k = 0; k < 8; k++) {
            gugu[k][i] = (k + 2) * (i + 1);
            printf("%dX%d= %2d ", k + 2, i + 1, gugu[k][i]);
            fprintf(wfp, "%dX%d= %2d ", k + 2, i + 1, gugu[k][i]);
        }
        printf("\n");
        fprintf(wfp, "\n");
    }
    printf("\n");
    fprintf(wfp, "\n");
    fclose(wfp);
 
 
    // 08-09) 
    int i, size;
    char imsi[100];
    char* p;
    char old, new;
 
    printf("문자열: ");
    gets(imsi);
 
    printf("문자들: ");
    scanf(" %c %c", &old, &new);
 
    size = strlen(imsi);
    
    p = (char*)malloc((sizeof(char) * size) + 1);
 
    strcpy(p, imsi);
 
    printf("변환: ");
    for (i = size - 1; i >= 0 ; i--) {
        if (p[i] == old) *(p + i) = new;
        printf("%c", p[i]);
    }
    printf("\n");
 
 
    // 08-09) 
    int i, size;
    char imsi[100];
    char* p;
    char old, new;
    
    printf("기존 문자열: ");
    gets(imsi);
    size = strlen(imsi);
    p = (char*)malloc((sizeof(char) * size) + 1);
    strcpy(p, imsi);
 
    printf("문자들: ");
    scanf(" %c %c", &old, &new);
 
    for (i = 0 ; i < size ; i++) {
        if (*(p + i) == old) {
            *(p + i) = new;
        }
    }
 
    upper_lower(p);
 
    printf("변환 문자열: ");
    for (i = size - 1; i >= 0; i--) {
        printf("%c", p[i]);
    }
    printf("\n");
    free(p);
 
 
    // 09-응용9-2) 
    char car = 'A';
    int top = 0;
    char stack[5];
    int answer;
 
    do {
        printf("<1> push, <2> pop, <3> stop: ");
        scanf("%d", &answer);
 
        switch (answer) {
        case 1:
            if (top < 5) {
                stack[top] = car;
                printf("%c차 push \n", stack[top]);
                top++; 
                car++; 
            }
            else printf("push 불가 \n");
            break;
        case 2:
            if (top > 0) {
                top--;
                car--;
                printf("%c차 pop \n", stack[top]);
                stack[top] = ' ';
            }
            else printf("pop 불가 \n");
            break;
        case 3:
            printf("현재 남은 차는 %d대 입니다. \n", top); break;
        default: printf("잘못 입력했습니다. \n"); break;
        }
 
    } while (answer != 3);
 
 
    // 09-08) 
    char ary[25] = "ITCookBook $%& 1234";
    char* p;
    int i;
    p = ary;
    int diff = 'a' - 'A';
    
    for (i = sizeof(ary) - 2; i >= 0; i--) {
        if (p[i] >= 'a' && p[i] <= 'z') p[i] -= diff;
        else if (*(p + i) >= 'A' && *(p + i) <= 'Z') *(p + i) += diff;
        printf("%c", *(p + i));
    }
    printf("\n");
 
    
    // 09-09) 
    int i, k, tmp;
    char s[100];
    char* p;
    
    printf("입력: ");
    gets(s);
    p = s;
 
    printf("결과: ");
    for (i = 0; i < strlen(s); i++) {
        for (k = i + 1; k < strlen(s); k++) {
            if (*(p + i) < *(p + k)) {
                tmp = *(p + i);
                *(p + i) = *(p + k);
                *(p + k) = tmp;
            }
        }
        printf("%c", *(p + i));
    }
    printf("\n");
 
 
    // 09-09) 
    int i, k, tmp;
    char s[100];
    char* p;
 
    printf("기존: ");
    gets(s);
    p = s;
 
    printf("결과: ");
    for (i = 0; i < strlen(s); i++) {
        for (k = i + 1; k < strlen(s); k++) {
            if (p[i] > p[k]) {
                tmp = p[i];
                p[i] = p[k];
                p[k] = tmp;
            }
        }
        printf("%c", p[i]);
    }
    printf("\n");
 
 
    // 10-예제29) 
    int i, k, num;
    char dup = 'N';
    int lotto[6] = { 0, };
 
    i = 0;
 
    srand((unsigned)time(NULL));
 
    while (1) {
        num = getLotto();
 
        for (k = 0; k < 6; k++)
            if (lotto[k] == num) 
                dup = 'Y';
 
        if (dup == 'N')
            lotto[i++] = num;
        else 
            dup = 'N';
 
        if (i == 6) break;
    }
 
    for (i = 0; i < 6; i++) {
        printf("%d ", lotto[i]);
    }
    printf("\n");
 
 
    // 10-08)
    char in[100], out[100];
 
    printf("문자열: ");
    gets(in);
 
    strcpy(out, upper_lower_re(in));
 
    printf("변환 결과 => %s \n", out);
 
 
    // 10-09)
    int diceNum[10] = { 0, };
    int dice1, dice2;
    int equalCount = 0;
    int i;
    char dup = 'N';
 
    srand((unsigned)time(NULL));
 
    while (1) {
        dice1 = throwDice();
        dice2 = throwDice();
 
        if (equalCount == 10) break;
 
        if (dice1 == dice2) dup = 'Y';
        else dup = 'N';
 
        if (dup = 'Y') {
            diceNum[equalCount] = dice1;
            equalCount++;
        }
    }
 
    printf("같은 숫자 => ");
    for (i = 0; i < 10; i++) {
        printf("%d ", diceNum[i]);
    }
    printf("\n");
 
 
    // 10-09) 
    int diceNum[10] = { 0, };
    int i;
    char dup = 'N';
    int* p = diceNum;
 
    srand((unsigned)time(NULL));
 
    int dice1, dice2;
    for (i = 0; i < 10;) {
        dice1 = throwDice();
        dice2 = throwDice();
 
        if (dice1 == dice2) dup = 'Y';
        else dup = 'N';
 
        if (dup = 'Y') {
            p[i] = dice1;
            i++;
        }
    }
    printf("같은 숫자 => ");
    for (i = 0; i < 10; i++) {
        printf("%d ", p[i]);
    }
    printf("\n");
 
 
    // 11-예제30) 
    int i, k;
    int gugu[8][9];
 
    FILE* wfp;
    wfp = fopen("c:\\cookc\\gugu0618.txt", "w");
 
    for (i = 2; i < 10; i++) {
        printf("#제%d단# ", i);
        fprintf(wfp, "#제%d단# ", i);
    }
    printf("\n");
    fprintf(wfp, "\n");
 
    for (i = 0; i < 9; i++) {
        for (k = 0; k < 8; k++) {
            gugu[k][i] = (k + 2) * (i + 1);
            printf("%dX%d= %2d ", k + 2, i + 1, gugu[k][i]);
            fprintf(wfp, "%dX%d= %2d ", k + 2, i + 1, gugu[k][i]);
        }
        printf("\n");
        fprintf(wfp, "\n");
    }
    printf("\n");
    fprintf(wfp, "\n");
    fclose(wfp);
 
 
    // 11-07) 
    int i = 0;
    char s[100];
 
    FILE* rfp;
    rfp = fopen("c:\\windows\\win.ini", "r");
 
    while (1) {
        fgets(s, 100, rfp);
 
        if (feof(rfp))break;
 
        printf("%d : %s", i + 1, s);
        i++;
    }
    printf("\n");
    fclose(rfp);
 
 
    // 11-07)
    int size;
    char imsi[100];
    char* p;
 
    FILE* rfp;
    rfp = fopen("c:\\windows\\win.ini", "r");
 
    int i = 0;
    while (1) {
        fgets(imsi, 100, rfp);
        size = strlen(imsi);
 
        if (feof(rfp)) break;
 
        p = (char*)malloc((sizeof(char) * size) + 1);
        strcpy(p, imsi);
 
        printf("%d : %s", i + 1, p);
        i++;
    }
    printf("\n");
    fclose(rfp);
    free(p);
 
 
    // 11-08) 
    int num, i;
 
    FILE* wfp;
    wfp = fopen("c:\\cookc\\rand0618.txt", "w");
 
    srand((unsigned)time(NULL));
 
    for (i = 0; i < 5; i++) {
        num = rand() % 100 + 1;
        printf("추출 숫자 => %d \n", num);
        fprintf(wfp, "추출 숫자 => %d \n", num);
    }
    printf("\n");
    fprintf(wfp, "\n");
    fclose(wfp);
 
 
    // 12-04) 
    int* p;
    int i = 0;
    int hap = 0;
    int num;
 
    printf("랜덤 숫자 => ");
    srand((unsigned)time(NULL));
 
    num = rand() % 100 + 1;
 
    p = (int*)malloc(sizeof(int) * 1);
    p[i] = num;
    printf("%d ", p[i]);
    hap = hap + p[i];
    i = 2;
 
    while (1) {
        num = rand() % 100 + 1;
 
        p = (int*)realloc(p, sizeof(int) * i);
        p[i - 1] = num;
 
        if (p[i - 1] == 99 && i > 2) break;
 
        printf("%d ", p[i - 1]);
        hap = hap + p[i - 1];
        i++;
    }
    printf("\n랜덤 합계 => %d \n", hap);
    free(p);
 
 
    // 12-04)
    int* p;
    int i = 0;
    int num;
    int hap = 0;
 
    FILE* wfp;
    wfp = fopen("c:\\cookc\\randhap0618.txt", "w");
 
    srand((unsigned)time(NULL));
    printf("랜덤 숫자 => ");
    fprintf(wfp, "랜덤 숫자 => ");
 
    p = (int*)malloc(sizeof(int) * 1);
 
    num = rand() % 100 + 1;
    p[i] = num;
 
    printf("%d ", p[i]);
    fprintf(wfp, "%d ", p[i]);
 
    hap = hap + p[i];
    i = 2;
 
    while (1) {
        p = (int*)realloc(p, sizeof(int) * i);
 
        num = rand() % 100 + 1;
        p[i - 1] = num;
 
        if (p[i - 1] == 99 && i > 2) break;
 
        printf("%d ", p[i - 1]);
        fprintf(wfp, "%d ", p[i - 1]);
 
        hap = hap + p[i - 1];
        i++;
    }
    printf("\n");
    fprintf(wfp, "\n");
 
    printf("랜덤 합계 => %d \n", hap);
    fprintf(wfp, "랜덤 합계 => %d \n", hap);
 
    fclose(wfp);
    free(p);
 
 
    // 12-07)
    int i, size;
    char* p[5];
    char imsi[100];
 
    FILE* rfp;
    rfp = fopen("c:\\windows\\win.ini", "r");
 
    for (i = 0; i < 5; i++) {
        fgets(imsi, 100, rfp);
        size = strlen(imsi);
 
        p[i] = (char*)malloc((sizeof(char) * size) + 1);
        strcpy(p[i], imsi);
 
        printf("%d : %s", i + 1, p[i]);
    }
 
    for (i = 4; i >= 0; i--) {
        printf("%d : %s", i + 1, p[i]);
    }
    fclose(rfp);
    for (i = 0; i < 5; i++) {
        free(p[i]);
    }
    
 
 
    // 13-예제34)
    struct student {
        char name[10];
        int age;
    };
 
    struct student s;
    struct student* p;
    p = &s;
 
    int i, cnt;
 
    printf("입력할 학생 수: ");
    scanf("%d", &cnt);
 
    p = (struct student*)malloc(sizeof(struct student) * cnt);
 
    for (i = 0; i < cnt; i++) {
        printf("이름과 나이 입력: ");
        scanf("%s %d", p[i].name, &p[i].age);
    }
 
    printf("\n-- 학생 명단 --\n");
    for (i = 0; i < cnt; i++) {
        printf("이름: %s, 나이: %d \n", p[i].name, p[i].age);
    }
    free(p);
 
 
    // 13-예제34)
    int i, cnt;
 
    struct student {
        char name[10];
        int age;
    };
 
    struct student s;
    struct student* p;
    p = &s;
 
    printf("입력 학생 수: ");
    scanf("%d", &cnt);
 
    p = (struct student*)malloc(sizeof(struct student) * cnt);
 
    for (i = 0; i < cnt; i++) {
        printf("이름, 나이: ");
        scanf("%s %d", p[i].name, &p[i].age);
    }
 
    printf("\n- 학생 명단 --\n");
    for (i = 0; i < cnt; i++) {
        printf("이름: %s, 나이: %d \n", p[i].name, p[i].age);
    }
    free(p);
 
    
    // 13-예제36) 
    enum month {
        Jan = 1, Fab, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
    };
 
    enum month mm;
 
    printf("확인하고 싶은 달은? ");
    scanf("%d", &mm); // 열거형 변수에 값 대입
 
    switch (mm) {
    case Jan: printf("%d월은 Jan. \n", mm); break;
    case Fab: printf("%d월은 Fab. \n", mm); break;
    case Mar: printf("%d월은 Mar. \n", mm); break;
    case Apr: printf("%d월은 Apr. \n", mm); break;
    case May: printf("%d월은 May. \n", mm); break;
    case Jun: printf("%d월은 Jun. \n", mm); break;
    case Jul: printf("%d월은 Jul. \n", mm); break;
    case Aug: printf("%d월은 Aug. \n", mm); break;
    case Sep: printf("%d월은 Sep. \n", mm); break;
    case Oct: printf("%d월은 Oct. \n", mm); break;
    case Nov: printf("%d월은 Nov. \n", mm); break;
    case Dec: printf("%d월은 Dec. \n", mm); break;
    default: printf("잘못 입력. \n"); break;
    }
 
 
    // 13-09)
    enum season{spring, summer, fall, winter};
 
    enum season ss;
 
    ss = summer;
 
    if (ss = summer) printf("지금은 여름.\n");
    else printf("여름은 아님.\n");
 
 
    // 13-10) 
    typedef struct _employee {
        union nm {
            char name[10];
            char dept[10];
        };
        union nm nm;
 
        union id {
            char jumin[20];
            char phone[13];
        };
        union id id;
    } employee;
 
    employee e1;
 
    printf("이름 또는 부서 => ");
    scanf("%s", e1.nm.name);
    printf("주소 또는 번호 => ");
    scanf("%s", e1.id.jumin);
 
    printf("\n-- 직원 명단 --\n");
    printf("이름/부서: %s\n", e1.nm.dept);
    printf("주소/번호: %s\n", e1.id.phone);
 
 
    // 13-11)
    struct student {
        char name[10];
        int avg;
    };
 
    struct student s;
    struct student* p;
    p = &s;
 
    printf("이름: ");
    scanf("%s", p->name);
    printf("점수: ");
    scanf("%d", &p->avg);
 
    printf("\n-- 성적표 --\n");
    printf("이름: %s, 점수: %d \n", p->name, p->avg);
 
 
    // 13-11) 
    typedef struct _student_re {
        char name[10];
        int avg;
    } student_re;
 
    student_re sr;
    student_re* pr;
    pr = &sr;
 
    int i, cnt;
 
    printf("학생 수: ");
    scanf("%d", &cnt);
 
    pr = (struct _student_re*)malloc(sizeof(struct _student_re) * cnt);
 
    printf("\n-- 정보 입력 --\n");
    for (i = 0; i < cnt; i++) {
        printf("이름, 점수: ");
        scanf("%s %d", pr[i].name, &pr[i].avg);
    }
 
    printf("\n-- 성적 출력 --\n");
    for (i = 0; i < cnt; i++) {
        printf("이름: %s, 점수: %d \n", pr[i].name, pr[i].avg);
    }
    free(pr);
}