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计算在一个伪数组中,对于给定下标距离数组起始点的偏移量--C和指针,第八章第6题

2022-07-02 15:02:28  阅读:39  来源: 互联网

标签:loc 数组 pt -- 偏移量 int arrayinfo offset dimension


不知道该如何实现如下功能:

函数offset()接受的可变参数:array_offset(arrayinfo,6,3,1)。

有没有办法控制可变参数的部分?从而程序自己读取输入的下标,并作为参数传递,而不是每次需要在函数参数上进行修改?例如想要计算在四维伪数组下的坐标偏移,不需要对array_offset()进行直接修改:array_offset(arrayinfo,6,3,1,1)。

 

# include <stdio.h>
# include <stdarg.h>
# include <stdlib.h>

int array_offset(int arrayinfo[], ...);
int calculation(int* pt, int* arrayinfo);

int main()

{
    int dimension;
    int result;
    
    puts("How many dimension you need?");
    scanf("%d", &dimension);
    
    int* arrayinfo = (int*)malloc((dimension * 2 + 1) * sizeof(int)); 

    if (arrayinfo == NULL)
    {
        puts("Failed to allocate the memory.");
        exit(1);
    }
    else
       *arrayinfo = dimension;

    for (int i=1,j=0; j < dimension ;j++,i+=2)  //例如3维,需要6个数值,作为每个维度的上下限;
    {
        printf("The dimension %d ,low_limit:\n", j+1);
        scanf("%d", &arrayinfo[i]);
        printf("The dimension %d ,high_limit:\n", j+1);
        scanf("%d", &arrayinfo[i+1]);
    }

    result = array_offset(arrayinfo,6,3,1);

    printf("the loc is %d. ",result);

    
    free(arrayinfo);  //free()
    return 0;

}

int array_offset(int*arrayinfo, ...)
{

    if (*arrayinfo < 1 || *arrayinfo >10)
        return -1;

    for (int i = 1; i < sizeof(arrayinfo); i+=2)  //对该维度上下标限制的检查,防止下限大于上限
    {
        if (arrayinfo[i] > arrayinfo[i + 1])
        {
            printf("For the dimension %d,the low_limits is bigger than the relevant high_limits.\n",i);
            return -1;
        }
    }
    
    va_list var_arg;
    va_start(var_arg, arrayinfo);

    int* pt = (int*)malloc((*arrayinfo) * sizeof(int));  //为下标申请空间
    if (pt == NULL)
    {
        puts("Failed to allocate the memory.");
        exit(1);
    }


    for (int i = 0; i < *arrayinfo; i++)   //存储下标
    {
        pt[i] = va_arg(var_arg, int);
    }
    
    int k = 0;
    for (int j = 2; k < *arrayinfo; j += 2,k++)        //对下标的检查,防止不在规定的上下限之间
    {
        if (pt[k] < arrayinfo[j - 1] ||  pt[k] > arrayinfo[j])
            return -1;
    }

    
    int loc;
    loc = calculation(pt,arrayinfo);
    free(pt);   //free()

    return loc;

}

int calculation(int* pt, int* arrayinfo)     //对偏移量的计算
{

    int loc ;
    int i = 4;
    int count = 1;
    int lim = sizeof(pt)-1;
    
    loc =(*pt) - arrayinfo[1];
    while (count < lim)
    {
        loc *=(*(arrayinfo+i) - *(arrayinfo+i-1) + 1);
        loc += pt[count] - *(arrayinfo+i-1);
        i += 2;
        count++;
    }
    return loc;
}

 

标签:loc,数组,pt,--,偏移量,int,arrayinfo,offset,dimension
来源: https://www.cnblogs.com/muyangbeihai/p/16437574.html

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