C语言二维数组与指针和参数传递

1.大小与参数传递

#include
//参数也可以是：int br[],int n
void print_ar(int (*br)[4],int row,int col)
//void print_ar(int [3][4],int row,int col)
//void print_ar(int [][4],int row,int col)
{ 
    sizeof(br);
    
    for(int i=0;i 
结果：
 
  1  2  3  4
  5  6  7  8
  9 10 11 12
8
48
 
2.练习题
 
#include
#include

int main()
{
    int ar[5][2]={1,2,3,4,5,6,7,8,9,10};
    int (*p)[2]=&ar[1];/
        ++i;
    }
    if(i == row)
    return -1;
    int j= col-1;
    while(j>=0 && val=0&&val == br[i][j])
    {
        pos=i*col+j;
    }
    return pos;
}

int main()
{
    int ar[4][5]=
    {
        2,4,6,8,10,
        12,14,16,18,20,
        24,27,29,32,33,
        38,45,56,78,90
    };
    int val;
    scanf("%d",&val);
    int pos=findvalue(ar,4,5,val);
    if(pos !=-1)
    {
	printf("第%d个元素n",pos+1);
    printf("行数:%d 列数:%dn",pos/5+1,pos%5+1);}
}
 
结果：
 
90
第20个元素
行数:4 列数:5
 
4.折半查询
 
#include
#include
int findvalue(int (*br)[5],int row,int col,int val)
{
    assert(br !=NULL);
    int * ip = (int*)br;
    int left=0,right=row*col-1;
    int pos=-1;
    while(left <= right)
    {
        int mid=(right-left)/2+left;
        if(valip[mid])
        {
            left=mid+1;
        }
        else
        {
            pos=mid;
            break;
        }
    }
    return pos;
}

int main()
{
    int ar[4][5]=
    {
        2,4,6,8,10,
        12,14,16,18,20,
        24,27,29,32,33,
        38,45,56,78,90
    };
    int val;
    scanf("%d",&val);
    int pos=findvalue(ar,4,5,val);
    if(pos !=-1)
    {
	printf("第%d个元素n",pos+1);
    printf("行数:%d 列数:%dn",pos/5+1,pos%5+1);}
}