C语言新手 请大家看看这段代码错在哪里了 谢谢了

下面这段代码 调试时候出现 declaration syntax error 出错 
请问应该怎么改啊 
#include<stdio.h>
#include<stdlib.h>
struct person
{
    char name[100];
    char tel[100];
    char addr[100];
};
char filename[100];
FILE *fp;
void append();
void creat();
void search();
void delete();
void output();
void seek()void append()         <===============就这有一出错误declaration syntax error
{
    struct person one;
    if((fp=fopen(filename,"a"))==NULL)
    {
         printf("\ncan't open the telebook !");
 exit(0);
    }
    printf("\n input name and address \n");
    scanf("%s%s%s",one.name,one.tel,one.addr);
    fprintf(fp,"%-100s%-100s%-100s\n",one.name,one.tel,one.addr);
    fclose(fp);
 }
void creat()
{
    struct person one;
    long s1;
    printf("\n input  name:");
    scanf("%s",filename);
    if((fp=fopen(filename,"w"))==NULL)
    {
         printf("\ncan't create!");
 exit(0);
    }
    fprintf(fp,"%-100s%-100s%-100s\n","name ","phonenumber","address");
    printf("\nplease input the name phonenumber and address!(end by 0)\n");
    scanf("%s",one.name);
    while(strcmp(one.name,"0"))
    {
         scanf("%s%s",one.tel,one.addr);
         fprintf(fp,"%-100s%-100s%-100s\n",one.name,one.tel,one.addr);
         scanf("%s",one.name);
    }
    fclose(fp);
}
void search()
{
    int k=0;
    char namekey[8];
    struct person one;
    printf("\n input name:");
    scanf("%s",namekey);
    if((fp=fopen(filename,"rb"))==NULL)
    {
         printf("\ncan't open the telebook!");
 exit(0);
    }
    while(!feof(fp))
    {
         fscanf(fp,"%s%s%s\n",one.name,one.tel,one.addr);
         if(!strcmp(namekey,one.name))
    {
         printf("\n\n found,like:");
         printf("\n%-100s%-100s%-100s",one.name,one.tel,one.addr);
         k=1;
    }
}
    if(!k)
  printf("\n not find \n");
    fclose(fp);
}
void delete()
{
    int m,k=0,flag;
    long offset1,offset2;
    char namekey[8], valid[4];
    struct person one;
    printf("\n input name:");
    scanf("%s",namekey);
    if((fp=fopen(filename,"r+"))==NULL)
    {
         printf("\ncan't open ");
 exit(0);
    }
         while(!feof(fp))
    {
         offset1=ftell(fp);
         fscanf(fp,"%s%s%s\n",one.name,one.tel,one.addr);
         if(!strcmp(namekey,one.name))
    {
         k=1;
         break;
    }
    }
    if(k)
    {
        printf("\nhave found,record like");
        printf("\n%-100s%-100s%-100s",one.name,one.tel,one.addr);
        printf("\n****delete,choose  1;undelete,choose  0*****:\n");
        scanf("%d",&m);
        if(m)
        {
     seek(fp,offset1,SEEK_SET);
             fprintf(fp,"%-100s%-100s%-100s\n","","","");
        }
    }
    else
             printf("\nnot found!\n");
             fclose(fp);
}
void output()
{
      struct person one;
      if((fp=fopen(filename,"r"))==NULL)
      {
            printf("\ncan't open telebook !\n");
    exit(0);
      }
      printf("\n\n%100s\n","T E L E B O O K");
      while(!feof(fp))
      {
           fscanf(fp,"%s%s%s\n",one.name,one.tel,one.addr);
           printf("%-100s%-100s%-100s",one.name,one.tel,one.addr);
    }
    fclose(fp);
}
main()
{
    int m;
    creat();
    while(1)
    {
          printf("*****************************************");
          printf("\n*        add             press 1     *");
          printf("\n*        search          press 2     *");
          printf("\n*        delete          press 3     *");
          printf("\n*        output          press 4     *");
          printf("\n*        exit            press 5     *\n");
          printf("*****************************************\n\n");
          scanf("%d",&m);    if(m>=0&&m<=5)
    {
          switch(m)
          {
                 case 1: append();
                 break;
                 case 2: search();
                 break;
                 case 3: delete();
                 break;
                 case 4: output();
                 break;
 case 5: exit(0);
         }
   printf("\n\n ok\n\n");
   }
  else
         printf("\n\n error\n\n");
 }
}