C - 高度な関数 - 関数を最大限に活用する(関数ポインタ、関数引数)

Head First C
原著

開発環境

• OS: macOS High Sierra - Apple
• IDE(統合開発環境): Xcode - Apple
• プログラミング言語: C

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)、エクササイズ(p. 321)を取り組んでみる。

エクササイズ(p. 321)

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

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

typedef int (*fn_type)(char *);

int const NUM_ADS = 7;
char *ADS[] = {
    "William: SBM GSOH likes sports, TV, dining",
    "Matt: SWM NS likes art, movies, theater",
    "Luis: SLM ND likes books, theater, art",
    "Mike: DWM DS likes trucks, sports and bieber",
    "Peter: SAM likes chess, working out and art",
    "Josh: SJM likes sports, movies and theater",
    "Jed: DBM likes theater, books and dining"
};
int sports_no_bieber(char *s) {
    return strstr(s, "sports") && !strstr(s, "bieber");
}
int sports_or_workout(char *s) {
    return strstr(s, "sports") || strstr(s, "working");
}
int ns_theater(char *s) {
    return strstr(s, "NS") && strstr(s, "theater");
}
int arts_theater_or_dining(char *s) {
    return strstr(s, "art") || strstr(s, "theater") || strstr(s, "dining");
}
void find(fn_type match) {
    puts("検索結果：");
    puts("--------------------------------------------------");
    for (int i = 0; i < NUM_ADS; i++) {
        if (match(ADS[i])) {
            printf("%s\n", ADS[i]);
        }
    }
    puts("--------------------------------------------------");
}
int main(int argc, const char * argv[]) {
    fn_type fns[] = {
        sports_no_bieber,
        sports_or_workout,
        ns_theater,
        arts_theater_or_dining,
        NULL
    };
    
    for (size_t i = 0; fns[i] != NULL; i++) {
        find(fns[i]);
    }
    return 0;
}

入出力結果(Terminal)

検索結果：
--------------------------------------------------
William: SBM GSOH likes sports, TV, dining
Josh: SJM likes sports, movies and theater
--------------------------------------------------
検索結果：
--------------------------------------------------
William: SBM GSOH likes sports, TV, dining
Mike: DWM DS likes trucks, sports and bieber
Peter: SAM likes chess, working out and art
Josh: SJM likes sports, movies and theater
--------------------------------------------------
検索結果：
--------------------------------------------------
Matt: SWM NS likes art, movies, theater
--------------------------------------------------
検索結果：
--------------------------------------------------
William: SBM GSOH likes sports, TV, dining
Matt: SWM NS likes art, movies, theater
Luis: SLM ND likes books, theater, art
Peter: SAM likes chess, working out and art
Josh: SJM likes sports, movies and theater
Jed: DBM likes theater, books and dining
--------------------------------------------------
Program ended with exit code: 0