我给你几个版本:
1.

#include<stdio.h>
#include<stdlib.h>
#define MAXSIZE 100

typedef struct
{
int elem[MAXSIZE] ;
int len ;
} SQLIST;

void creatsqlist ( SQLIST &L );

int main( void )
{
SQLIST L ;
creatsqlist (L);

printf ( " %d", L.elem[1] );

system ( "pause" );

return 0;
}//函数main结束

void creatsqlist ( SQLIST &L ) //创建线性表
{
int i;

scanf( "%d", &L.len );

for ( i = 0; i < L.len; i++ )
scanf ( "%d", &L.elem[i] );
}

2.
#include<stdio.h>
#include<stdlib.h>
#define MAXSIZE 100

typedef struct
{
int elem[MAXSIZE] ;
int len ;
} SQLIST;

void creatsqlist (SQLIST *L) ;

int main( void )
{
SQLIST L ;
creatsqlist (&L);

printf ( " %d", L.elem[1] );

system ( "pause" );

return 0;
}//函数main结束

void creatsqlist (SQLIST *L) //创建线性表
{
int i;

scanf( "%d", &L->len );

for ( i = 0; i < L->len; i++ )
scanf ( "%d", &L->elem[i] );
}

#include<stdio.h>
#include<stdlib.h>
#define MAXSIZE 100

typedef struct
{
int elem[MAXSIZE] ;
int len ;
} SQLIST;

void creatsqlist ( SQLIST L );

int main( void )
{
SQLIST L ;
creatsqlist ( L );

printf ( " %d ", L.elem[2] );

system ( "pause" );

return 0;
}//函数main结束

void creatsqlist ( SQLIST L ) //创建线性表
{
int i;

scanf( "%d", &L.len );

for ( i = 0; i < L.len; i++ )
scanf ( "%d", &L.elem[i] );
}

因为行参不能改变实参.
你这里用指针做参数,但是函数里用的也是地址.