C学习之顺序表(数组篇)

动态顺序表，能动态分配内存，静态顺序表在编译时已分配内存。

#include <stdio.h>#include <conio.h>#define MaxSize 10typedef int ElemType;typedef struct {ElemType *elem;int length;int listsize;}Sqlist;void InitSqlist(Sqlist *L){L->elem=(ElemType *)malloc(MaxSize*sizeof(ElemType));if(!L->elem) exit(0);L->length=0;L->listsize=MaxSize;}void InsertSqlist(Sqlist *L,int i,ElemType item){ElemType *base;int t;if(i<1||i>L->length+1) exit(0);if(L->length==L->listsize){base=(ElemType *)realloc(L->elem,(L->listsize+10)*sizeof(ElemType));L->elem=base;L->listsize=L->listsize+10;}for(t=L->length-1;t>=i-1;i--){L->elem[t+1]=L->elem[t];}L->elem[i-1]=item;L->length=L->length+1;}void DelElem(Sqlist *L,int i){int t;if(i<1||i>L->length) exit(0);for(t=i;t<L->length;t++){L->elem[t-1]=L->elem[t];}L->length--;}void main(){Sqlist list;int i;InitSqlist(&list);for(i=0;i<15;i++){InsertSqlist(&list,i+1,i+1);}printf("/nThe content of the list is/n");for(i=0;i<list.length;i++){printf("%d ",list.elem[i]);}DelElem(&list,5);printf("/nDelete the fifth element/n");for(i=0;i<list.length;i++){printf("%d ",list.elem[i]);}while(1);} 

编程时出现问题：为什么在main（）里定义了Sqlist *plist这个，使用时怎么说未定义？