1>delete.obj : error LNK2019: 无法解析的外部符号 "char _cdecl readfile(class,该怎么解决

1>delete.obj : error LNK2019: 无法解析的外部符号 "char __cdecl readfile(class

#include <iostream>

#include <windows.h>

#include <string>

#include <fstream>

#include <math.h>

#include "file_operate.h"

#include "delete.h"

using namespace std;


void refresh(int start,int end,fstream &f)//从start开始写到end

{

    fstream f3;

    f3.open("reftmp.txt",ios::binary|ios::out|ios::app);

    char tp;

    f.seekg(start,ios::beg);

    for(int i=start/8; i<end/8; i++)

    {

        tp=readfile(f);

        writefile(tp,f3);

    }

    f3.close();

}


void Delete()

{

    char table_name[20];//buf判断数据类型缓冲

    char tp;

    char *str=".txt";

    char tmp[30];

    int i=0,w=0;

    int num=0;//属性的个数

    int length[10];//每个属性的长度

    char name[20][20];//每个属性的名称

    int start=0,end=0;

    int power=0;//是否有删除的条目

    tmp[i]=' ';

    string cmpa,cmpb,value;

    cout<<"Delete from ";

    cin>>table_name;

    cmpa=string(table_name);

    fstream f1;

    f1.open("model.txt",ios::binary|ios::in);//判断是否存在表;

o:

    tmp[i]=readfile(f1);

    i++;

    if(f1.eof()==0)

    {

        while(tmp[i-1]!=',')

        {

            tmp[i]=readfile(f1);

            i++;

        }

        tmp[i-1]='\0';

        cmpb=string(tmp);

        if(cmpa==cmpb)//表名存在

        {

            int nn=1;//读取逗号个数

            f1.seekg(-8,ios::cur);

p:

            tp=readfile(f1);//读取属性个数及每个属性长度及属性名称

            if(tp!='!')

            {

                tp=readfile(f1);

                while(tp!=',')

                {

                    name[num][w]=tp;

                    w++;

                    tp=readfile(f1);

                }

                name[num][w]='\0';

                w=0;

                tp=readfile(f1);

                while(nn<=1)

                {

                    tp=readfile(f1);

                    if(tp==',')

                    {

                        nn++;

                    }


                }

                tp=readfile(f1);

                length[num]=(int)tp-48;

                tp=readfile(f1);

                if(tp<='9'&&tp>='0')

                {