2018年2月16日金曜日

開発環境

Head First C ―頭とからだで覚えるCの基本 (David Griffiths (著)、Dawn Griffiths (著)、中田 秀基 (監修)、木下 哲也 (翻訳)、オライリージャパン)の7章(高度な関数 - 関数を最大限に活用する)、長いエクササイズ(p. 329)を取り組んでみる。

長いエクササイズ(p. 329)

//
//  main.c
//  sample1
//
//  Created by kamimura on 2018/02/14.
//  Copyright © 2018 kamimura. All rights reserved.
//

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

int scores[] = {543, 323, 32, 554, 11, 3, 112};
int scores_n = 7;

void scores_display() {
    for (size_t i = 0; i < scores_n; i++) {
        printf("%i\n", scores[i]);
    }
}
typedef int (*fn_type)(const void *, const void*);
int compare_scores(const void * score_a, const void * score_b) {
    puts(__func__);
    int a = *(int*)score_a;
    int b = *(int*)score_b;
    
    return a - b;
}
int compare_scores_desc(const void * score_a, const void * score_b) {
    puts(__func__);
    return compare_scores(score_b, score_a);
}

fn_type comps[] = {compare_scores, compare_scores_desc, NULL};

typedef struct {
    int width;
    int height;
} Rectangle;

int rects_n = 5;
void rects_display(Rectangle rects[]) {
    for (size_t i = 0; i < rects_n; i++) {
        printf("%i x %i\n", rects[i].width, rects[i].height);
    }
}
int compare_areas(const void * a, const void * b) {
    puts(__func__);
    Rectangle *rect_a = (Rectangle*)a;
    Rectangle *rect_b = (Rectangle*)b;
    int area_a = rect_a->width * rect_a->height;
    int area_b = rect_b->width * rect_b->height;
    return area_a - area_b;
}
int compare_names(const void * a, const void * b) {
    puts(__func__);
    char **name_a = (char**)a;
    char **name_b = (char **)b;
    return strcmp(*name_a, *name_b);
}
int compare_area_desc(const void * a, const void * b) {
    puts(__func__);
    return compare_areas(b, a);
}
int compare_names_desc(const void *a, const void *b) {
    puts(__func__);
    return compare_names(b, a);
}
int names_n = 5;
void names_display(char *names[]) {
    for (size_t i = 0; i < names_n; i++) {
        puts(names[i]);
    }
}
fn_type rect_comps[] = {compare_areas, compare_area_desc, NULL};
fn_type name_comps[] = {compare_names, compare_names_desc, NULL};

int main(int argc, const char * argv[]) {
    for (size_t i = 0; comps[i] != NULL; i++) {
        puts("before");
        scores_display();
        qsort(scores, scores_n, sizeof(int), comps[i]);
        puts("after");
        scores_display();
    }
    Rectangle rects[5];
    int nums[5] = {5, 1, 4, 2, 3};
    for (size_t i = 0; i < 5; i++) {
        rects[i] = (Rectangle){.width=1, .height=nums[i]};
    }
    for (size_t i = 0; rect_comps[i] != NULL; i++) {
        puts("before");
        rects_display(rects);
        qsort(rects, rects_n, sizeof(Rectangle), rect_comps[i]);
        puts("after");
        rects_display(rects);
    }
    char *names[] = {"e", "a", "d", "b", "c"};
    for (size_t i = 0; name_comps[i] != NULL; i++) {
        puts("before");
        names_display(names);
        qsort(names, names_n, sizeof(char*), name_comps[i]);
        puts("after");
        names_display(names);
    }
    return 0;
}

入出力結果(Terminal)

before
543
323
32
554
11
3
112
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
compare_scores
after
3
11
32
112
323
543
554
before
3
11
32
112
323
543
554
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
compare_scores_desc
compare_scores
after
554
543
323
112
32
11
3
before
1 x 5
1 x 1
1 x 4
1 x 2
1 x 3
compare_areas
compare_areas
compare_areas
compare_areas
compare_areas
compare_areas
compare_areas
compare_areas
compare_areas
after
1 x 1
1 x 2
1 x 3
1 x 4
1 x 5
before
1 x 1
1 x 2
1 x 3
1 x 4
1 x 5
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
compare_area_desc
compare_areas
after
1 x 5
1 x 4
1 x 3
1 x 2
1 x 1
before
e
a
d
b
c
compare_names
compare_names
compare_names
compare_names
compare_names
compare_names
compare_names
compare_names
compare_names
after
a
b
c
d
e
before
a
b
c
d
e
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
compare_names_desc
compare_names
after
e
d
c
b
a
Program ended with exit code: 0

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