c++ - 奇怪的错误: label 'loopend' used but not defined, expected unqualified-id before “if ” (same error for “goto” and “' }' token ”

Question

这是我的代码。我不确定为什么会出现这些错误，并且我尽可能地仔细查看了。

我知道第一个错误似乎发生是因为我的“loopend:”标签
在我的程序结束时似乎距离太远了。那是可能的原因吗？

至于其余的，我不知道为什么会 pop 。

在“if(Choice ==“OSI”)区域之后，这似乎是一个问题。

#include "stdlib.h"
#include <iostream>
#include <string>
#include <sstream>
#include <fstream>
 using namespace std;

int main() {
    ifstream pswdchk ("OSIUser.setting");
    string Password[5];
    string Passload[5];
    string NormPass;
    string tocmd;
    int Chickenvar=0;
    int CMD=1;
    string Choice;
    string Title;
    string style = "-";
    string Bdr = "";
    string Columnten = "";
    string Columnten1 = "";
    string Columnten2 = "";
    string WaitColumn = "";
    std::string opt1;
    std::string opt2;
    std::string opt3;
    std::string opt4;
    std::string opt5;
    std::string opt6;
loop:
    system("color 3b");
    if(CMD==0) {
    cout <<"Invalid Command.\n\n>";
}
if (Chickenvar==1) {
    cout << "\n\nChicken 'style' to chicken a stylish chicken test. Chicken 'exit' to chicken\nprogram. KFC is love, KFC is life.\n\nCHICKEN GOES HERE>";
}
    if (CMD==1) {
    if (Chickenvar==0) {
        cout <<"OBCLS Version 0.3\nType exit to quit.\n\n>";
    }
}
CMD=0;

cin >>Choice;
if(Choice=="exit") {
goto loopend;
}
if(Choice=="style") {
    using namespace std; //It seems I need it here too?
    CMD=1;
    system("color 2e");
    system("CLS");
    opt1 = "\n1:                     Style 1";
    opt2 = "\n2:                     Style 2";
    opt3 = "\n3:                     Style 3";
    opt4 = "\n4:                     Style 4";
    opt5 = "\n5:                     Style 5";
    opt6 = "\n6:                    No Style";
    std::cout << "Hello!" << "\nThis is a test of the OIS Styling       System..." << "\nChoose a style:" << opt1 << opt2 << opt3 << opt4 << opt5 << opt6 <<"\n";
    std::string Choice = "";
ChoiceRetry:

    cout << "\n>";
    cin >> Choice;
    if (Choice == "6") {
        cout << "Viewing styleless window:\n\n";
        goto ChoiceYes;
    }

    cout << "\n\n";
    if (Choice == "1") {
        Columnten = "----------";
        Columnten1 = " ----------";
        Columnten2 = "---------";
        Bdr = "| ";
        WaitColumn = " ---------PRESS--ENTER--------";
        style = "1";
        goto ChoiceYes;
    }
    if (Choice == "2") {
        Columnten = "          ";
        Columnten1 = "o         ";
        Columnten2 = "          o";
        Bdr = " ";
        WaitColumn = "o         PRESS  ENTER        o";
        style = "2";
        goto ChoiceYes;
    }
    if (Choice == "3") {
        Columnten = "//////////";
        Columnten1 = "//////////";
        Columnten2 = "//////////";
        Bdr = "/";
        WaitColumn = "/////////PRESS  ENTER/////////";
        style = "3";
        goto ChoiceYes;
    }
    if (Choice == "4") {
        Columnten = "==========";
        Columnten1 = "==========";
        Columnten2 = "==========";
        Bdr = "=";
        WaitColumn = "=========PRESS==ENTER=========";
        style = "4";
        goto ChoiceYes;
    }
    if (Choice == "5") {
        Columnten = "##########";
        Columnten1 = " #########";
        Columnten2 = "######### ";
        Bdr = "#";
        WaitColumn = " ####### PRESS  ENTER ####### ";
        style = "5";
        goto ChoiceYes;
    }
    cout << "Invalid input.";
    goto ChoiceRetry;
ChoiceYes:
    Title = " EXAMPLE: ";
    //string ColumnTitle = Columnten1, Title, Columnten2;(USE COUT)
    //string Column = Columnten1, Columnten, Columnten2; (USE COUT)
    cout << Columnten1<< Title<< Columnten2 << "\n" ;
    string TYPE = "This is an example window   ";
    cout << Bdr<< TYPE<< Bdr<< "\n";
    TYPE = "         for style ";
    cout << Bdr<< TYPE<< style ;
    TYPE = ".       ";
    cout << TYPE<<Bdr<< "\n";
    cout << WaitColumn;





    std::cin.clear();
    std::cin.ignore(32767, '\n');
    std::cin.get();
    system("CLS");
}
if (Choice=="Chicken"){
    if(Chickenvar==0){  
    Chickenvar=1;
    cout<<"Chicken Mode Enabled";
    goto Chicken_toggle_end;
}
    if(Chickenvar==1){
    Chickenvar=0;
    goto Chicken_toggle_end;
    cout<<"Chicken Mode Disabled";
    }
    Chicken_toggle_end:
    CMD=1;
    goto loop;
}
if (Choice=="cmd"){
    system("CLS");
    system("color 6e");
    cout <<"This will not work on systems with a disabled command prompt\n\n";
    system("cmd");
    CMD=1;
    system("CLS");
}
if (Choice=="help"){
    CMD=1;
    cout<<"To run commands using CMD, type 'cmd'.\nTo test the styling system, type 'style'.\nTo exit the program, type 'exit'.\nTo run the GUI, type 'OSI'.\n\n";

}
if (Choice=="OSI"){
    Styleloop:
    system("CLS");
    system("color 2a");
    cout<<"\n\nChoose the system style.\nEnter 1-5, 6 for no style:";
    cin>>Choice;
    if (Choice == "1") {
        Columnten = "----------";
        Columnten1 = " ----------";
        Columnten2 = "---------";
        Bdr = "| ";
        WaitColumn = "- - - - - - - - - - - - - - - - - - - - - - - - - ";
        style = "1";
        goto Styleend;
    }
    if (Choice == "2") {
        Columnten = "          ";
        Columnten1 = "o         ";
        Columnten2 = "          o";
        Bdr = " ";
        WaitColumn = "o                                               o";
        style = "2";
        goto Styleend;
    }
    if (Choice == "3") {
        Columnten = "//////////";
        Columnten1 = "//////////";
        Columnten2 = "//////////";
        Bdr = "/";
        WaitColumn = "//////////////////     ++++     ////////////////";
        style = "3";
        goto Styleend;
    }
    if (Choice == "4") {
        Columnten = "==========";
        Columnten1 = "==========";
        Columnten2 = "==========";
        Bdr = "=";
        WaitColumn = "================================================";
        style = "4";
        goto Styleend;
    }
    if (Choice == "5") {
        Columnten = "##########";
        Columnten1 = " #########";
        Columnten2 = "######### ";
        Bdr = "#";
        WaitColumn = " ############################################## ";
        style = "5";
        goto Styleend;
    }
    if (Choice == "6") {
    string style = "-";
    string Bdr = " ";
    string Columnten = " ";
    string Columnten1 = " ";
    string Columnten2 = " ";
    string WaitColumn = " ";
    goto Styleend;
    }
    goto Styleloop;
    Styleend:
    OSImainloop:
system("CLS");  
opt1 = "                                              ";
opt2 = "                 OSI v0.2.3                   ";
opt3 = "                                              ";
opt4 = "          1:                    Exit          ";
opt5 = "          2:                  Log in          ";
opt6 = "                                              ";
Title="  Welcome to OSI GUI v1.0   ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nEnter A Number:";


cin>>Choice;
if(Choice=="1"){
    goto exitmain;
}
if (Choice=="2"){
    goto OSImainloopbreak;
}
goto OSImainloop;
OSImainloopbreak:
    OSIlogloop:
system("CLS");  
opt1 = " Type exit to go back                         ";
opt2 = "                                              ";
opt3 = "                                              ";
opt4 = "             - ENTER PASSWORD -               ";
opt5 = "       Type 'new' to create a new user.       ";
opt6 = "                                              ";
Title="  User Login Access System  ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nEnter Password:";
cin >>Choice;
if (Choice=="exit"){
goto OSImainloop;
}
if (Choice=="new"){
newuser:
system("CLS;");
opt1 = " Type exit to abort operation                 ";
opt2 = "                                              ";    
opt3 = "          Please enter a password             ";
opt4 = "             for your new user.               ";
opt5 = "                   .....                      ";
opt6 = "                                              ";
Title="  User Login Access System  ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nEnter Your New Password:";
cin >>NormPass;
if (NormPass=="new"){
system("CLS;");
opt1 = "                                              ";    
opt2 = "       Sorry. This password is reserved       ";
opt3 = "            for the new user command.         ";
opt4 = "                                              ";
opt5 = "                -Press Enter-                 ";
opt6 = "                                              ";
Title="           -Error-          ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\n";
std::cin.clear();
std::cin.ignore(32767, '\n');
std::cin.get();
goto newuser;
}
if (NormPass=="exit"){
    goto OSImainloopbreak;
}
PassGenRetry:
ofstream passgen;
passgen.open ("OSIUser.setting");
if (passgen.is_open()) {
    passgen <<NormPass;
}
else {
filebadloop:
system("CLS;");
opt1 = "                                              ";
opt2 = "          The file 'Users.passwf' did         ";
opt3 = "             not open successfully.           ";
opt4 = "         A new user cannot be created.        ";
opt5 = "            1=Retry        2=Abort            ";
opt6 = "                                              ";
Title="  User Login Access System  ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nEnter A Number:";
cin>>Choice;
if (Choice=="1"){
    cout<<"Press Enter to attempt to open 'Users.passwf' again...";
    std::cin.clear();
    std::cin.ignore(32767, '\n');
    std::cin.get();
    goto PassGenRetry;
}
if (Choice=="2"){
    goto OSImainloopbreak;
}
goto filebadloop;
}
system("CLS;");
opt1 = "                                              ";
opt2 = "   Password has been successsfully installed. ";
opt3 = "          Press Enter to continue.            ";
opt4 = "                                              ";
opt5 = "                    .....                     ";
opt6 = "                                              ";
Title="  User Login Access System  ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\n";
std::cin.clear();
std::cin.ignore(32767, '\n');
std::cin.get();
goto OSIlogloop;
}
Pswdchkloop:
if (pswdchk.is_open()){
    for(int i = 0; i < 5; ++i){

    pswdchk>>Password[i];
}
}
else {
chkbadloop:
system("CLS;");
opt1 = "                                              ";
opt2 = "          The file 'Users.passwf' did         ";
opt3 = "             not open successfully.           ";
opt4 = "           Passwords failed to load.          ";
opt5 = "            1=Retry        2=Abort            ";
opt6 = "                                              ";
Title="  User Login Access System  ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nEnter A Number:";
cin>>Choice;
if (Choice=="1"){
    cout<<"Press Enter to attempt to open 'Users.passwf' again...";
    std::cin.clear();
    std::cin.ignore(32767, '\n');
    std::cin.get();
    goto Pswdchkloop;
}
if (Choice=="2"){
    goto OSImainloop;
}
goto chkbadloop;
} 
if (Choice==Password[0]){

    goto OSIlogloopbreak;
}
goto OSIlogloop;
OSIlogloopbreak:
if (Chickenvar==1){
cout<<"ADMIN ENABLED\n\nPress Enter";
std::cin.clear();
std::cin.ignore(32767, '\n');
std::cin.get();
}
else {
    cout<<"User initiated.\n\nPress Enter"; 
    std::cin.clear();
    std::cin.ignore(32767, '\n');
    std::cin.get();
}
loopmainmenu:
system("color 3b");
system("CLS;");
if (Chickenvar==1){
opt1 = " Welcome Admin                         v0.2.3 ";
}
else {
    opt1 = " Welcome User                          v0.2.3 ";
}
opt2 = "                 Options:                     ";
opt3 = "-Programs                                     ";
opt4 = "-Options                                      ";
opt5 = "-About                                        ";
opt6 = "-Exit                                         ";
Title="         - Welcome -        ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nChoose an option:";
cin>>Choice;
for(unsigned int n = 0; n < Choice.length(); ++n) {
Choice[n] = tolower(Choice[n]);
}
if (Choice=="exit"){
goto OSImainloop;
}
if (Choice=="about"){
system("CLS;");
system("color 7e");
opt1 = "           OSI GUI and Command Shell          ";
opt2 = "                   System                     ";
opt3 = "                                              ";
opt4 = "              By Olivier Poirier              ";
opt5 = "                                              ";
opt6 = "                                              ";
Title="         - About -          ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\n";
std::cin.clear();
std::cin.ignore(32767, '\n');
std::cin.get();
}
if (Choice=="programs"){
prgmloop:
system("color 2a");
system("CLS");  
opt1 = "                                              ";
if (Chickenvar==1){
opt1 = "                     - Hidden Items Revealed -";
}
opt2 = "-Word                                         ";
opt3 = "-Text Adventure                               ";
opt4 = "-Exit                                         ";
opt5 = "                                              ";
if (Chickenvar==1){
opt5 = "-Special Documents                            ";
}
opt6 = "                                              ";
Title="  User Login Access System  ";
cout << Columnten1<< Title<< Columnten2 << "\n" ;
cout<< Bdr<< opt1<< Bdr<<"\n";
cout<< Bdr<< opt2<< Bdr<<"\n";
cout<< Bdr<< opt3<< Bdr<<"\n";
cout<< Bdr<< opt4<< Bdr<<"\n";
cout<< Bdr<< opt5<< Bdr<<"\n";
cout<< Bdr<< opt6<< Bdr<<"\n";
cout<<WaitColumn<<"\nEnter Password:";
cin >>Choice;
for(unsigned int n = 0; n < Choice.length(); ++n) {
Choice[n] = tolower(Choice[n]);
}
if (Choice=="exit"){
goto loopmainmenu;

}

}
}
goto loopmainmenu;
exitmain:
CMD=1;
system("CLS");
}
if (Choice=="clear"){
CMD=1;
system("CLS");
}   

goto loop;
loopend:
return 0;
}

Answer 1

我将您的代码粘贴到VS2013中的新源文件中，然后在“编辑”菜单上的“高级”->“设置文档格式”中。这可以整理代码的缩进和布局。然后，从视觉上可以清楚地看出，您已关闭int main()函数，而此代码紧随其后，编译器拒绝了该代码。您的标签loopend在函数外部，因此在函数内部不可见。

int main() {
    ... ... ...
    goto loopmainmenu;
exitmain:
    CMD = 1;
    system("CLS");
}

然后遵循此:

if (Choice == "clear"){
    CMD = 1;
    system("CLS");
}

goto loop;
loopend:
return 0;
}

您需要将此代码移回 int main()。

作为建议，您应该替换所有这些 goto语句。

if (Choice == "Chicken"){
    if (Chickenvar == 0){
        Chickenvar = 1;
        cout << "Chicken Mode Enabled";
        goto Chicken_toggle_end;
    }
    if (Chickenvar == 1){
        Chickenvar = 0;
        goto Chicken_toggle_end;
        cout << "Chicken Mode Disabled";
    }
Chicken_toggle_end:
    CMD = 1;
    goto loop;
}

变成

if (Choice == "Chicken"){
    if (Chickenvar == 0){
        Chickenvar = 1;
        cout << "Chicken Mode Enabled";
    }
    if (Chickenvar == 1){
        Chickenvar = 0;
        cout << "Chicken Mode Disabled";
    }
    CMD = 1;
}

而不是 goto loop将逻辑放入 while循环中。 Goto逻辑很难理解。