C言語の「bsearch()関数」のサンプルプログラムです。
- bsearch() ソートされた配列を二分木検索 (binary search) する
- POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD
- #include <stdlib.h>
- void *bsearch( const void *key, const void *base, size_t nmemb, size_t size, int ( *compare )( const void *arg1, const void *arg2 ) );
- compareが指す関数は次の値を返さなければならない
-
戻り値 意味 0より小さい arg1がarg2より小さい場合 0 arg1とarg2が等しい場合 0より大きい arg1がarg2より大きい場合
-
目次
サンプルコード
[bsearch.c]
#include <stdlib.h> /* bsearch() */
#include <ctype.h> /* tolower() */
#include <stdio.h>
typedef enum{
FALSE = 0,
TRUE = 1
} bool_e;
typedef enum{
CH_OTHER = 0,
CH_ALPHA,
CH_NUM
} char_type_e;
int charCompare( const void *a, const void *b );
bool_e isAlphabet( char ch );
bool_e isNumber( char ch );
char_type_e whatTypeOfChar( char ch );
char getInput( void );
int main( void )
{
char ch;
char_type_e t;printf( "*** It ends when you enter a character that is neither alphabetic nor numeric. ***\n" );
do{
ch = getInput();t = whatTypeOfChar( ch );
switch( t ){
case CH_ALPHA:
printf( " `%c' is alphabet.\n", ch );
break;
case CH_NUM:
printf( " `%c' is number.\n", ch );
break;
default:
printf( " `%c' is neither an alphabet nor a number.\n", ch );
}
}while( t != CH_OTHER );return 0;
}
/* 2つの文字を比較する */
int charCompare( const void *a, const void *b )
{
return *( char *)a - *( char *)b ;
}
bool_e isAlphabet( char ch )
{
static char alphabet = "abcdefghijklmnopqrstuvwxyz";
void *ptr;
bool_e bRet;/* ソートされた配列を二分木検索 (binary search) する */
ptr = bsearch( &ch, alphabet, 26, sizeof( char ), charCompare );
bRet = TRUE;
if( ptr == NULL )
bRet = FALSE;return bRet;
}
bool_e isNumber( char ch )
{
static char number = "0123456789";
void *ptr;
bool_e bRet;/* ソートされた配列を二分木検索 (binary search) する */
ptr = bsearch( &ch, number, 10, sizeof( char ), charCompare );
bRet = TRUE;
if( ptr == NULL )
bRet = FALSE;return bRet;
}
char_type_e whatTypeOfChar( char ch )
{
char_type_e chType = CH_OTHER;
if( isAlphabet( ch ) )
chType = CH_ALPHA;
else if( isNumber( ch ) )
chType = CH_NUM;return chType;
}
char getInput( void )
{
char ch;fputs( "char?: ", stdout ); fflush( stdout );
scanf( " %c", &ch ); /* 頭のホワイトスペースは無視 */
// fseek( stdin, 0L, SEEK_END ); /* 残りの入力は捨てる */
while( getchar() != '\n' ); /* 残りの入力は捨てる */
ch = tolower( ch ); /* 大文字小文字の違いは無視 */return ch;
}
実行例
Cygwin 3.3.6-1, gcc (GCC) 11.3.0
$ gcc -Wall -O2 -o bsearch_cygwin bsearch.c
$
$ ./bsearch_cygwin.exe
*** It ends when you enter a character that is neither alphabetic nor numeric. ***
char?: 0
`0' is number.
char?: 1
`1' is number.
char?: 89
`8' is number.
char?: 9
`9' is number.
char?: a
`a' is alphabet.
char?: b
`b' is alphabet.
char?: y
`y' is alphabet.
char?: z
`z' is alphabet.
char?: Z
`z' is alphabet.
char?: A
`a' is alphabet.
char?: +
`+' is neither an alphabet nor a number.
$
CentOS Stream 9, gcc (GCC) 11.3.1
$ gcc -Wall -O2 -o bsearch_centos9 bsearch.c
$
$ ./bsearch_centos9
*** It ends when you enter a character that is neither alphabetic nor numeric. ***
char?: abc
`a' is alphabet.
char?: +123xyz
`+' is neither an alphabet nor a number.
$
Microsoft Windows 10, Visual Studio 2022, x86 Native Tools Command Prompt for VS 2022
>cl /nologo /utf-8 /Fe:bsearch_msvc bsearch.c
bsearch.c
>bsearch_msvc.exe
*** It ends when you enter a character that is neither alphabetic nor numeric. ***
char?: a
`a' is alphabet.
char?: X
`x' is alphabet.
char?: -
`-' is neither an alphabet nor a number.>
