VS中C++报错【error LNK2005: _main 已经在 .obj 中定义】

Question

main.h头文件内容如下

#pragma once
#ifndef C0_COMPILER_MAIN_H
#define C0_COMPILER_MAIN_H

#include <fstream>
#include <map>
#include <vector>
#include <set>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <ctype.h>
#include <iomanip>//格式化输出
#include "tool.h"

//using namespace std;
using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::ios;
using std::fstream;
using std::map;
using std::stringstream;

// Restricts
const int maxIdentLength = 100;
const int maxLineLength = 100;
const int keywordCount = 15;//14+1
const int maxDigit = 15;
const int maxInt = 100000000;

//type
typedef char alpha[maxIdentLength + 1]; // Alphabet letter should be restricted to maxIdentLength
typedef enum {
    identi, // 0
    constsy, // 1
    intsy, charsy, // 2, 3
    voidsy, // 4
    intcon, charcon, stringcon, // 5, 6, 7
    plus, minus, times, idiv, // 8, 9, 10, 11
    eql, neq, gtr, geq, lss, leq, // 12, 13, 14, 15, 16, 17
    becomes, // 18
    lparent, rparent, lbrack, rbrack, lbrace, rbrace, // 19, 20, 21, 22, 23, 24
    comma, semicolon, colon, // 25, 26, 27
    ifsy, elsesy, // 28, 29
    switchsy, casesy, defaultsy, // 30, 31, 32
    forsy, // 33
    scanfsy, printfsy, // 34, 35
    mainsy, // 36
    returnsy, // 37
    whilesy//38
} symbol; // All C0 reserved words
typedef enum {
    consts,
    vars,
    params,
    funcs
} kind; // All C0 kinds
typedef enum {
    ints, chars, voids
} type; // All C0 types
typedef struct {
    char name[maxIdentLength]; // Identifier
    kind cls; // Const or variable or parameter or function
    type typ; // Int or char or void
    int addr;
    int length;
    int level; // Block level where elements lies
} tabElement; // Symbol table element
typedef struct {
    string ioperator;
    string operand1;
    string operand2;
    string operand3;
} infixNotation;//putout format
typedef enum {
    LeadingZero, NumRangeExceed, ExclamationMark,
    EmptyChar, IllegalChar, QuotMarkLost,
    IllegalStr, StrRangeExceed, UnknownWord,
    SignedZero, NumErr, NotVarFunc,
    IdRepeat, CharConErr, ConDefTypeErr,
    ArrIndexErr, DefHeadErr, IdNotDefine,
    IllegalFact, IdKindNotMatch, StepLenZero,
    CaseNotCon, ParamCountExceed, IllegalType,
    PrintfSyLost, ScanfSyLost, ReturnSyLost,
    DefaultSyLost, ColonLost, CaseSyLost,
    SwitchSyLost, PlusLost, ForSyLost,
    IfSyLost, BecomesSyLost, VoidSyLost,
    LeftBraceLost, RightBraceLost, LeftParentLost,
    RightParentLost, RightBrackLost, IdLost,
    SemicolonLost, AssignSyLost, TypeDefLost,
    StepLenLost, StateErr, IllegalSyntax
} errorType;
// Static elements
extern alpha keywords[];
extern symbol keySymbols[];
extern map<char, symbol> specialSymbols;

// Global Variables changing all the way
extern char line[]; // One source code line
extern char ch; // Currently reading character
extern alpha token;
extern symbol sy;
extern int inum;
extern char str[];
extern int level;
extern fstream inputFile;
extern fstream infixFile;
// Lengths for global variables
extern int lineLength; // Currently reading line length
extern int stringLength;

// Pointers(Indices) for global variables
extern int charPtr;
extern int linePtr;
extern std::vector<int> funcPtrs;
extern int idTablePtr;
// Tables
extern std::vector<tabElement> idTable;
extern std::vector<tabElement> staticTable;
extern std::vector<infixNotation> infixTable;
// Flags
extern bool errorFlag;
extern bool skipFlag;//用于判断句子完整性，如果为0，说明不完整

// Lexical functions
void nextch(); // Store one source code line into line[] and store one char into ch
void insymbol(); // Read one symbol, sy stores symbol type, inum stores contents
//symbol functions
void setup();
// erro functions
void error(int errorNum); // Output error position & error number
void skipUntil(symbol nexts[], int length);
void setup(); // Set up reserved words

// id_Table functions
void insertTable(kind cls, type typ, const char name[], int length, int level, int addr);
void insertStatic(string function, kind cls, type typ, const char name[], int length, int level);
void popElement();
void popLocals();
int lookUp(const char* name); // Return index of identifier in table
int lookUpStatic(const char* functionName); // For function
int lookUpStatic(const char* functionName, const char* identifier); // For local variable or parameter
bool isDefinable(char name[]);
int findCurrentFunc();
void printTable();

//infixNotation function
void insertInfix(string ioperator, string operand1, string operand2, string operand3);
void outputInfixes();
string createTempVar();
//
// praser actions

void program();
void constState();
void constDef();
void globalVarState();
void varState();
void varDef();
void funcWithRetDef();
void funcWithoutRetDef();
void defHead(type* returnType, char identifier[]);
void parameter();
void parameterTable();
void complexState();
void mainDef();
type factor(string& infixString);
type term(string& infixString);
type expression(string& infixString);
void assignState();
void ifState();
void judgement(string& infixString); // Judgement inside if statement
void loopState();
void whileState();
void conditionState();
void conditionTable(type firstType, string switchElement, string endSwitchLabel);
void conditionBranch(type firstType, string switchElement, string endSwitchLabel);
void conditionDefault();
void funcWithRetCall(string& infixString);
void funcWithoutRetCall();
void valueParamTable(int idIndex);
void returnState();
void scanfState();
void printfState();
void stateList();
void statement();
void integer(string& infixString);

// Infixes optimization
void optimizeInfixes();

// Target code generations
void mipsProgram(string mipsFileName);
#endif //C0_COMPILER_MAIN_H

请问这个问题该如何解决

Answer 1

应该是那些函数声明在其他文件中声明过了吧。😂具体的看不出来