warning C4700:local variable 'l' used without having been in

你的main函数中的l变量应作为全局变量,放在最最开始的那几行,在执行完函数时的过程中,l中三元素的值当然会变,但执行完,l就有返回执行前的状态了,函数在执行时会为括号中的各个参数创建一块空间,但执行完毕之后就会自动释放.例如你执行status status Initlist(sqlist l,int list_number)时,编译器先为l建一个复制品,名字也叫l,在执行完这个函数后,那个复制的l就没了,只剩下原来的l,你的status listinsert_sq(sqlist l,int i,elemtype e )也是这个毛病,++l.length只在函数中改变了那个复制品的length值,执行完这个函数后l.length还是原来那个l.length（比预期的总少一）,导致在执行插入操作后,程序输出总是少了最后一个数.
warning C4700:local variable 'l' used without having been initialized的意思是没对l初始化,initialized不是init的形容词形式吗?（不严格的说）你想想,是不是你的status Initlist(sqlist l,int list_number)这个函数只对你那个复制品l初始化了,其实l并没被初始化.
我写了一个没把l放在main（）外面做全局变量的程序,你看看是不是你想要的：
#include "stdio.h"
#include "stdlib.h"
#define ERROR 0
#define ok 1
#define OVERFLOW -2
#define list_init_size 100
#define listincrement 10
typedef int status;
typedef int elemtype;
typedef struct{
elemtype *elem;
int length;
int listsize;
}sqlist;
status Initlist(sqlist l,int list_number)
{if(list_number>list_init_size) return ERROR;
l.elem=(elemtype*)malloc(list_number*sizeof(elemtype));
if(!l.elem) exit(OVERFLOW);
l.length=0;
l.listsize=list_number;
return ok;
}
status listinsert_sq(sqlist l,int i,elemtype e )
{
elemtype *p,*q,*newbase;
if(il.length+1) return ERROR;
if(l.length>=l.listsize)
{
newbase=(elemtype*)realloc(l.elem,(l.listsize+listincrement)*sizeof(elemtype));
if(!newbase) return(OVERFLOW);
l.elem=newbase;
l.listsize+=listincrement;
}
q=&(l.elem[i-1]);
for(p=&(l.elem[l.length-1]);p>=q;--p) {*(p+1)=*p;}
*q=e;
//改动处
//++l.length;(这句话就没用了,写不写都成)
//改动处
return ok;
}
void outputlist(sqlist l)
{int j;
for(j=0;jlist_init_size) return ERROR;
l.elem=(elemtype*)malloc(n*sizeof(elemtype));
if(!l.elem) exit(OVERFLOW);
l.length=0;
l.listsize=n;
//改动处
printf("输入线性表元素：");
for(i=0;ilist_init_size) exit(0);//return ERROR;
l.elem=(elemtype*)malloc(list_number*sizeof(elemtype));
if(!l.elem) exit(OVERFLOW);
l.length=0;
l.listsize=list_number;
//return ok;
}
//改动处
/*status*/void listinsert_sq(int i,elemtype e )
//改一下返回类型
//改动处
{
elemtype *p,*q,*newbase;
if(il.length+1) exit(0);//return ERROR;
if(l.length>=l.listsize)
{
newbase=(elemtype*)realloc(l.elem,(l.listsize+listincrement)*sizeof(elemtype));
if(!newbase) exit(OVERFLOW);
l.elem=newbase;
l.listsize+=listincrement;
}
q=&(l.elem[i-1]);
for(p=&(l.elem[l.length-1]);p>=q;--p) *(p+1)=*p;
*q=e;
++l.length;
//return ok;
}
void outputlist()
{int j;
for(j=0;j