C言語初心者の学習記録

はじめに

今回はC言語の学習記録として探索について学びました。
学習記録として随時記載していきます。
特段の目的等はありませんので、ご了承ください

実行環境

・windows：Windows11Pro 23H2

課題１

関数ポインタ、文字列配列を題材にした問題

test.c

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

typedef enum {NO,YES} boolean;
typedef struct WordOps{
    void (*to_large)(char *);
    void (*to_small)(char *);
    void (*to_reverse)(char *);
}WordOps;

typedef struct Word{
    char text[32];
    WordOps *ops;
}Word;

void large(char *s);
void small(char *s);
void reverse(char *s);
void call_method(Word *w,int method);

void large(char *s){
    printf("before :%s\n",s);
    for(int i = 0;s[i]!= '\0';i++){
        s[i] = toupper((unsigned char)s[i]);
    }
    printf("after :%s\n",s);
}

void small(char *s){
    printf("before :%s\n",s);
    for(int i = 0;s[i]!= '\0';i++){
        s[i] = tolower((unsigned char)s[i]);
    }
    printf("after :%s\n",s);
}

void reverse(char *s){
    printf("before :%s\n",s);
    for(int i = 0;s[i] != '\0';i++){
        unsigned char c = s[i];
        if(isupper(c)){
            s[i] = tolower(c);
        }else if(islower(c)){
            s[i] = toupper(c);
        }
    }
    printf("after :%s\n",s);
}

void call_method(Word *w,int method){
    switch(method){
        case 0:w->ops->to_large(w->text);break;
        case 1:w->ops->to_small(w->text);break;
        case 2:w->ops->to_reverse(w->text);break;
    }
}
int main(){ 
    int select_func = 0;
    boolean select_flag = NO;
    WordOps ops = {large,small,reverse};
    Word words[] = {
        {"Apple",&ops},
        {"Banana",&ops},
        {"Cherry",&ops},
        {"Durian",&ops},
    };
    int words_num = sizeof(words)/sizeof(words[0]);

    while(select_flag == NO){
        printf("select func 0:LARGE,1;SMALL,2:REVERSE\n");
        scanf("%d",&select_func);
        if(0 <= select_func && select_func <= 2){
            select_flag = YES;
        }
    }

    if (select_func == 0)printf("YOUR SELECTION is LARGE\n");
    if (select_func == 1)printf("YOUR SELECTION is SMALL\n");
    if (select_func == 2)printf("YOUR SELECTION is REVERSE\n");

    for (int i = 0;i < words_num;i++)call_method(&words[i],select_func);

    return 0;
}