在C ++中使用条件语句中的字符

Question

I am trying to write a program which asks for tuition credits and for undergraduate or graduate classes. User enters the number of credits, then must enter U for undergraduate or G for graduate. I am having issues with the conditional statement, if the user enters U , then the price of the undergraduate credits will compute and output, similar with graduate. I am trying to enter U at the IF condition, but either one price or the other outputs.

#include <stdlib.h>                             
#include <iostream.h>                          

int main ()                                    
{                                             
 const double Under = 380.00 ; 
 const double Grad = 395.00 ;
 char U , G ; 
 double First, Second, Third, Fourth, Fifth, Sixth ;

 cout << endl << endl ;       
 cout << " To calculate your tuition enter the amount of credits, then enter type of"  ; 
 cout << endl ; 
 cout << " classes." ; 

 cout << endl << endl ; 
 cout << " Enter number of credits. " ; 
 cin >> First ; 
 cout << endl << endl ;

 cout << " Enter U for Undergraduate or G for Graduate: " ; 
 cin >> Second ; 

 cout << endl << endl ; 
 cout << " Your tuition total is: " ; 

 Third = First * Under ; 

 Fourth = First * Grad ; 

 if ( Second == U )
 cout << Third ;

 else 
 cout << Fourth ; 
 cout << endl << endl ; 

 system ("Pause");                      

 }                                               

Answer 1

You never give a value to U . Right now its content is garbage which is why you get random behavior. Try either assigning 'U' to your variable U or changing the confiditional to:

if( Second == 'U' )

Answer 2

Ok I see a few problems here.

The main one is that characters in C++ have single quotes, like this 'c' . This is most likely the cause of your error. Since you never initialized U anywhere, either do initialize it to 'U' or try

if ( Second == 'U' )
    cout << Third ;

Second, though this is not necessarily an error typing cout<<endl<<endl; is a little wasteful as it flushes the buffer for cout twice with only 1 character added in between. typing cout<<'\\n'<<endl; would fix that.

Answer 3

It is more or less all of the already stated:

1. Remove the declaration of char U since it is never used
2. Change the type of Second to char (remove from the double list and add char Second; )
3. Change the if statement to if ( ( Second == 'U' ) || ( Second == 'u' ) )

Answer 4

I don't see U = 'U' anywhere. You is declared at beginning, but never initialized. You U is just a variable. You have to assign the character 'U' in it.

Answer 5

第二个被声明为double，但看起来你希望用户输入一个字符。

Answer 6

use

using namespace std;

under header file