langc_algo_single_list.c

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

typedef struct ListElmt_ {
    void * data;
    struct ListElmt_ *next;
}ListElmt;


typedef struct List_ {
    int size;
    ListElmt *head;
    ListElmt *tail;
}List;


int list_init(List *plist)
{
    plist->size=0;
    plist->head = NULL;
    plist->tail = NULL;

    return 0;
}


int list_ins_last(List *plist, void *pdata)
{
    int ret=0;
    ListElmt *pNewElemt,*pNext;

    if( plist->size >= 0 ){

        pNewElemt = (ListElmt *) malloc( sizeof(ListElmt) );

        pNewElemt->data = pdata; // last node address  
        pNewElemt->next = NULL;

        if(plist->tail == NULL || plist->head == NULL){ // first insert elements

            plist->head = pNewElemt;
            plist->tail = pNewElemt;

        }else {  // second insert elements 

            if( plist->head != NULL){
                plist->tail->next = pNewElemt;
                plist->tail = pNewElemt;
            }else
                ret=-2; //error 1               
        }

        plist->size++;

        if(ret < 0)
            free(pNewElemt);

    }else
        ret = -1;   // error 1

    return ret;
}

int list_del_head(List *plist,void **pData) // for queue, dequeue
{
    int ret=0;
    int *pTest;
    ListElmt *tmp;

    if( plist->size > 0 && plist->head != NULL ){

            if(plist->head->next == NULL || plist->size == 1){ // last one, 

               *pData = plist->head->data;
                free(plist->head);

                // reset 
                plist->head = NULL;
                plist->tail = NULL;
                plist->size = 0;

                pTest = (int *)*pData;

            }else { // more than 1 

                *pData = plist->head->data;     // head's data      
                tmp = plist->head;
                plist->head = plist->head->next; // pop 


                free(tmp);

                pTest = (int *)*pData;

                plist->size--;
            }

    }else
        ret=-1;


    return ret;
}

int list_del_tail(List *plist,void **pData) // for stack, pop
{
    int ret=0;
    int *pTest,i;
    ListElmt *tmp;

    if( plist->size > 0 && plist->tail != NULL ){

        if(plist->size == 1) {

            tmp = plist->tail;
            *pData = tmp->data;
            free(tmp);

            //reset;
            plist->head = NULL;
            plist->tail = NULL;
            plist->size = 0;

        }else { //more than 2 elmts 

            tmp = plist->head;
            for(i=0;i<(plist->size-2);i++)
            {
                if(tmp->next != NULL)
                    tmp = tmp->next; // (tail-1) 
            }

            *pData = plist->tail->data;
            free(plist->tail);

            plist->tail = tmp;
            plist->size--;
        }
    }else
        ret=-1;

    return ret;
}


List list;

int main()
{
    int data[]={1,2,3,4,5,6,7,8,9,10};
    int pri=0;
    int i=0,j;
    int chk=0;

    ListElmt *pElmt,*pNext;
    int *pTestData;
    int *pTestData2;


    list_init(&list);


    for(j=0;j<5;j++)
    {
       for(i=0;i<4+j;i++)
        {

            chk = list_ins_last(&list,(void *)&data[i]);
            if(chk < 0)
                printf("error ins!!!!!!!!! chk=%d",chk);

            printf("enqueue %d/%d  data %d \n",i,list.size,data[i]);

        }

        printf("\n\n");

        for(i=0;i<3+j;i++)
        {
         //   chk = list_del_head(&list,(void **)&pTestData2 );
            chk = list_del_tail(&list,(void **)&pTestData2 );

            if(chk < 0)
                printf("error del !!!!!!!!! chk=%d",chk);

            printf("dequeue %d/%d data %d \n",i,list.size, *pTestData2);
        }
        printf("\n\n");
    }

    return 0;
}