#include    <stdio.h >
#define     SIZE    16

int     binarysearch    ( int  low, int  high,    int    Array[],  int  value ) ;
        
int    main ( void )
{
        
        int  i = 0;
        int  location;
        int  array [ SIZE ];
        int  key;
        
        for( i=0; i< SIZE ; i++ )
        {
            
             array [ i ] = 2* i;
            
        }
        printf( " insert number you want to check\n ");
        scanf(" %d ", &key );  
        location = binarysearch  ( 0, SIZE-1, array, key );
      
        if ( !location )       printf(" no this one\n ");
        else
        {
             printf( "Location in the array is %d \n" , location );
        }
        return       0;
}


int     binarysearch    ( int  low, int  high,   int    Array[],   int  value )

{
         
        int   middle ;
        
        while  ( low <= high )
        {
               middle = (low + high)/2 ;
               if  ( value == Array [ middle ] )       return    middle;
               else  if ( value < Array [ middle ])  
               {
                     high = middle -1;
               }
               else  
               {
                    low = middle +1 ;
               }
               
        }
        
        return  0;
        
}







              
               
                    

可以的你把scanf(" %d ",&key);改成 scanf("%d",&key);  %d前后不要加空格

scanf("%d", &key);

#include <stdio.h>

int main()
{
    int    key, array[10], i;

    for( i=0; i<10; i++ )
        array[i] = 2*i;
    printf("Please input one number:");
    scanf("%d", &key);
    for( i=0; i<10; i++ )
    {
        if( array[i] == key )
        {   printf("%d\n", i+1);
            break;
        }
    }
    if( i==10 )
        printf(" wu ci shu.\n");

    return 0;
}