C - 高度な関数 - 関数を最大限に活用する - 関数ポインタの作成方法

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)、 O’Reilly Media)の 7章(高度な関数 - 関数を最大限に活用する)、p.321(エクササイズ)の解答を求めてみる。

Makefile

main: main.c
	cc main.c && ./a.out

コード

main.c

#include <stdio.h>
#include <string.h>
int 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",
    "Josnh: 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, "sprots") || strstr(s, "working out");
}
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(int (*match)(char *))
{
    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 (*matchs[])(char *) = {sports_no_bieber,
                               sports_or_workout,
                               ns_theater,
                               arts_theater_or_dining,
                               NULL};
    for (size_t i = 0; matchs[i] != NULL; i++)
    {
        printf("%p\n", matchs[i]);
        find(matchs[i]);
    }
}

入出力結果(Terminal, Zsh)

% make
cc main.c && ./a.out
検索結果
--------------------
Josnh: SJM likes sports, movies and theater
--------------------
%