二分查找

#include<stdio.h>
void pp(){
          for(int i=0;i<20;i++){
                printf("%c",c);
            }
              printf(" \n");
}

int main(){
pp();
        int a[]={0,1,2,3,4,5,6,7,8,9,10};
        int lo=0,hi=9,mid;
        int x=5,pos=-1；
        while(lo<=hi){
                mid=(lo+hi)/2;
                printf("mid=%d\n",mid);
                    if(x<a[mid]){
                          hi=mid-1;
                  }else if(x>a[mid]){
                          lo=mid+1;
                  }else{
                              pos=mid;
                              break;
                        }
                     }
                          printf("%d\n",pos);
                            pp();
      return 0;                     

}