Question

我正在尝试学习c ++，而我遇到了if / else语句的问题。当我在没有打开和关闭支架的情况下嵌入它们时，我以为我把它们弄下来了，但是我尝试使用支架并且出错了。

有人可以指出错误以及如何解决问题，而不仅仅是答案;这样我就不会学到东西。

这是我的来源：

#include "stdafx.h"
#include <iostream>
using namespace std;

int main()
{
 signed long int RealNumber = 31710;
 int Guess;

 cout << "Lets see if you can guess my favorite number... \n";
 cout << "Type in a number and hit enter to see if you have guessed it correctly. \n";
 cout << "you should know this one Danielle. \n \n ";
 cin >> Guess;


 if (Guess == RealNumber)
 {
  cout << "Wow, you are amazing! \n";
  cout << "Would you like to be punched?";
 }
 else
 {
  if (Guess < RealNumber)
   cout << "The number is higher";
  else
   if (Guess > RealNumber)
    cout << "The number is lower";
   else
    cout << "That is impossible!"; //trying to make sure that if anthing but a number is entered that the program doesn't crash.
 }

}
 char f;  // used to make the program wait for input before closing. 
 cin >> f;

 return 0;

Answer 1

你的上方有一个额外的支架 -

char f; 
cin >> f;

这个右大括号与主要功能的初始大括号相匹配。

你在if / else嵌套中使用的支撑结构对我来说似乎很好。

这是一个提示 - 对于每个左大括号，立即键入右大括号，并为其添加注释。你不必永远使用这个'拐杖'，但作为一个学习编写代码的初学者，这个coudl非常有帮助。

第1步：

int main()
{
}//main

第2步：

int main()
{
    int foo; 
    cin >> foo; 
    if (foo < 100)
    {
        //todo 
    }// if (foo < 100)
}//main

第3步：

int main()
{
    int foo; 
    cin >> foo; 
    if (foo < 100)
    {
        cout << "foo is too small";
        cin >> foo; 
        if (foo < 100)
        {
            //todo 
        } // if (foo < 100), inner if statement 
    }// if (foo < 100)
}//main

等。

Answer 2

使用带有自动缩进的文本编辑器是个好主意。这可能会帮助您避免像这样的“简单”错误。

Answer 3

请看大卫的答案。我还想指出，通常情况下，您需要编写if-else代码，如下所示：

 if (Guess == RealNumber)
 {
   cout << "Wow, you are amazing! \n";
   cout << "Would you like to be punched?";
 }
 else if (Guess < RealNumber)
 {
   cout << "The number is higher";
 }
 else if (Guess > RealNumber)
 {
   cout << "The number is lower";
 }
 else
 {
    cout << "That is impossible!";
 }

或

 if (Guess == RealNumber)
 {
   cout << "Wow, you are amazing! \n";
   cout << "Would you like to be punched?";
 }
 else if (Guess < RealNumber)
   cout << "The number is higher";
 else if (Guess > RealNumber)
   cout << "The number is lower";
 else
    cout << "That is impossible!";

Answer 4

试试这个

#include <iostream>
using namespace std;

int main()
{
 signed long int RealNumber = 31710;
 int Guess;

 cout << "Lets see if you can guess my favorite number... \n";
 cout << "Type in a number and hit enter to see if you have guessed it correctly. \n";
 cout << "you should know this one Danielle. \n \n ";
 std::cin >> Guess;


 if (Guess == RealNumber)
 {
  cout << "Wow, you are amazing! \n";
  cout << "Would you like to be punched?";
 }
 else
 {
  if (Guess < RealNumber)
   cout << "The number is higher";
  else
   if (Guess > RealNumber)
    cout << "The number is lower";
   else
    cout << "That is impossible!"; //trying to make sure that if anthing but a number is entered that the program doesn't crash.
 }

 char f;  // used to make the program wait for input before closing. 
 std::cin >> f;

 return 0;
} // <-- this bracket was misplaced

您的main()括号错位了。

Answer 5

你应该使用{}，你有if-else链。编译器没有看到你如何缩进if-else（以“数字更高”开头）并且它将它看作if-elseif-else的一个平面。但是，在这种特殊情况下，我没有看到它导致您出现问题。

Answer 6

尝试计算开始和结束括号。

Answer 7

删除#include <stdafx.h>（如果这是Visual Studio项目，请在项目设置中关闭“预编译头”）。

在该大括号之前移动您在}大括号main后面放置的语句。

您不能在函数外部使用非声明语句。

干杯＆amp;第h

C ++ If / else / nesting问题

7 个答案: