写了个小程序，貌似还有错，求指点

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


typedef int DataType;
 struct SeqList
{
    int MAXNUM;
    int n;
    DataType *element;
};

typedef struct SeqList *PSeqList;

PSeqList creatList_seq(int m)
{
    PSeqList palist=(PSeqList)malloc(sizeof(struct SeqList));
    if(palist!=NULL)
    {
        palist->element=(int *)malloc(sizeof(int)*m);
        if(palist->element)
        {
            palist->element;
            palist->MAXNUM=m;
            palist->n=20;
            for(int i=0;i<palist->n-1;i++)
            {
                palist->element[i]=i+1;
               
            }
            return palist;
        }
        else
            free(palist);
    }
   
    printf("out of space!!\n");
    return NULL;
}


int isNULLList_seq( PSeqList palist)
{
    return(palist->n==0);
}
/*求x在palist所指顺序表中的下标*/
int locate_seq(PSeqList palist,DataType x)
{
    int q;
    for(q=0;q<palist->n;q++)
        if(palist->element[q]==x)
            return q;
    return -1;
}
/*在palist所指顺序表表中下标为p的元素之前插入元素x*/
int insertPre_seq(PSeqList palist,int p,DataType x)
{
    int q;
    if(palist->n>=palist->MAXNUM)
    {
        printf("overflow!\n");
        return 0;
    }
    if(p<0||p>palist->n)
    {
        printf("Not exist!\n");
        return 0;
    }
    for(q=palist->n-1;q>=p;q--)
    {
        palist->element[q+1]=palist->element[q];
    }
        palist->element[p]=x;
        palist->n=palist->n+1;    //元素个数加1
        return 1;
}

int main()
{
    PSeqList palist;

    palist=creatList_seq(40);
    for(int q=0;q<palist->n-1;q++)
             cout<<palist->element[q];
    cout<<endl;
    cout<<insertPre_seq( palist,4,1);
    cout<<endl;
    cout<<locate_seq(palist,3);
    cout<<endl;
    return 0;
}