处理结构指针数组的动态增长

Question

I have a problem about the growth of the struct pointer array.

An arrary of pointers to structure stored memory location.

But I'm not sure how many I will want to store.

I want dynamic growth of the array.

I also may need to remove one of the elements.

Code as follows：

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

struct dominate * realloct(int* dim_1, struct dominate *dominateList)
{
    int i;
    struct dominate *dominateList_temp = (struct dominate *)malloc(sizeof(struct dominate *)*(*dim_1+10));

    for(i = 0; i < *dim_1+10;i++)
    {
        if(i<*dim_1)
        {
            dominateList_temp[i] = dominateList[i];
            //memcpy(b[i], a[i], (long)(sizeof(int)*(*dim_1)));
        }
        else
            dominateList_temp[i] = (struct dominate *)malloc(sizeof(struct dominate *)*dim_1);
    }
    (*dim_1) = (*dim_1)+10;

    return dominateList_temp;
}

struct dominate
{
    double ID;
};

struct dominate *head;

int main()
{
    int i;
    struct dominate *dominateList;
    struct dominate *dominateList_temp;
    int dim_1 = 10;

    struct dominate *z[100];

    for(i = 0; i < 100; i++){
        head = (struct dominate *) malloc(sizeof(struct dominate *));
        head->ID = i;
        z[i] = head;
    }


    dominateList = (struct dominate *)malloc(sizeof(struct dominate *)*dim_1);

    for(i = 0; i < 100; i++){
        if(i == dim_1 )
        {
            dominateList_temp = realloct(&dim_1, dominateList);
            free(dominateList);
            dominateList = dominateList_temp;
        }
    }

    printf("%d \n\n", dim_1);

    for(i = 0; i < 100; i++){
        printf("%.2lf ", dominateList[i].ID);
        printf("\n");
    }   
    return 0;
}

I do not know how to modify this problem

if(i<*dim_1){
    dominateList_temp[i] = dominateList[i];
    //memcpy(dominateList_temp[i], dominateList[i], (long)(sizeof(struct dominate *)*dim_1);
}
else
    dominateList_temp[i] = (struct dominate *)malloc(sizeof(struct dominate *)*dim_1);

Also, if I want to delete an element of the array, how to do it?

Answer 1

In C++, just use an std::vector<dominate> :

std::vector<dominate> d1;
d1.push_back(dominate()); // add a default constructed dominate object

std::vector<dominate> d2(100); // construct a vector with 100 default constructed dominate objects
dominate dom = ..... ;
d2[45] = dom; 

Answer 2

Since you tagged this as both C and C++, I'll answer for just one of those: If you want such behavior in C++, you shouldn't implement it yourself. All of it is already done in the standard template library. Just use std::list (if you're doing lots of insert or remove from the middle, and accept a longer item lookup time) or std::vector (if you want fast item lookups, but accept longer times to insert or remove items from the middle of the list).

Looking at your code:

• you use C, so you may have mistagged it.
• you want std::list <dominate>