C - 高度な関数 - 関数を最大限に活用する(引数、関数ポインタ、変数)

Head First C
原著

開発環境

• OS: Windows 10 Pro
• IDE(統合開発環境): Visual Studio 2017 (Clang/C2(試験的))
• プログラミング言語: C(Visual 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)

コード

#include <stdlib.h> 
#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",
 "Josh: SJM likes sports, movies and theater",
 "Jed: DBM likes theater, books and dining"
};

bool sports_or_workout(char *s)
{
 return strstr(s, "sports") || strstr(s, "working out");
}

bool ns_theater(char *s)
{
 return strstr(s, "NS") && strstr(s, "theater");
}

bool arts_theater_or_dining(char *s)
{
 return strstr(s, "art") || strstr(s, "theater") || strstr(s, "dining");
}
void find(bool (*match)(char *s))
{
 puts("検索結果");
 puts("--------------------------------------------------");

 for (size_t i = 0; i < 7; i++)
 {
  if (match(ADS[i]))
  {
   printf("%s\n", ADS[i]);
  }
 }
 puts("--------------------------------------------------");
}

int main()
{
 bool(*matches[])(char *s) = { sports_or_workout, ns_theater, arts_theater_or_dining, NULL };

 for (size_t i = 0; matches[i] != NULL; i++)
 {
  find(matches[i]);
 }

 system("pause");
 return 0;
}

入出力結果(コマンドプロンプト)

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
--------------------------------------------------
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