help me. program dont work

[haiphonghponline]

i tried but its not working. help me

#include<iostream.h>
#include<math.h>
#include<conio.h>
#include<stdio.h>
#include<string.h>//is this neccesory
int main()
{
int add,sub,answer,done;
labelA:
cout<<"whats is the basic mathamatical operation you want to perform? \n";
cout<<"please answer with add-for addition sub-for subtraction.\n";//program prints this then become unresponsive.when the applications "close on exit" is unchecked from the properties.when it checked closes automatically. 
cin<<answer;
if (answer==add)
{
//program of addition
long double value1;
long double value2;
long double output1;

cout<<"Enter first number for addition. \n";
cin>>value1;
cout<<"Enter second number for addtion. \n";
cin>>value2;
output1=value1+value2;
cout<<"The sum of these two number: "<<output1;

goto labelA;

}
if (answer==sub)
{
//program of subtraction
long double sub1;
long double sub2;
long double ans2;

cout<<"Enter the first number for subtraction.\n";
cin>>sub1;
cout<<"Enter the second number for subtraction.\n";
cin>>sub2;
ans2=sub1-sub2;
cout<<"The sub of these two numbers are: "<< ans2;
goto labelA;
}
if (answer==done)
{cout<<"thank you for using this program.Good bye" <<endl;
getch();
}
return 0;
}
//any solutions will be greatly appreciated. 

[whitenite1]

@haiphonghponline

add, sub, done and answer probably should be set as strings, since you're wanting someone to type words and not integers.

[Duthomhas]

You are asking the user to type text ("add" or "sub") when your program is trying to read an integer.

You are also trying to compare answer to add -- a variable that has not been given an initial value. (Your compiler should be complaining about that to you!)

By the way, your compiler is ancient. I learned C++ after the standard library was actually standardized, so I don't know how to get a string using the classic iostream.h methods (at least, not safely).

You do need to input a string, then compare it with string operators to the strings "add" and "sub".

The other option would be to ask the user to input 1 for add and 2 for subtract, or something like that. Then read the integer and see if answer == 1 or if answer == 2. Etc.

Hope this helps.

[Nohj]

First off, I'd like to say, definitely a fan of the use of goto. I love it, although it's evil.

If you truly want the user to select add or subtract, you're going to want to make them strings. Same with answer. Also yeah, string.h(<string> works too) is necessary for using strings.

Lets say the user input's add:

if (answer[0]=='a') && (answer[1]=='d') && (answer[2]=='d') {
long double value1;
long double value2;
long double output1;

cout<<"Enter first number for addition. \n";
cin>>value1;
cout<<"Enter second number for addition. \n";
cin>>value2;
output1=value1+value2;
cout<<"The sum of these two numbers are: "<<output1;

goto labelA;

}

It'll compare the first character in answer to the character 'a', then 'd', and 'd' again. Same thing goes for sub.

EDIT: If you want, add an else statement, incase they misspell add, the else will pick it up and could say "Invalid, try again". Then goto start; (Where start: will be somewhere above where it asks to input add or sub.)
Don't get too much into the habit of goto's though. Didn't notice where LabelA: was.


Second off, you want to use the namespace std. so under your #includes type
using namespace std;

This way you won't have to type std::cout and std::cin over and over again, you can just type cout, and cin. (Since you're already using cout and cin, you need it)



PS: After you go to LabelA, ask if the user is done. And add a loop over everything so if he's not done, he can type add or sub again. Didn't notice where LabelA: was.

EDIT2: I'm 98% sure you don't need

#include<math.h>
#include<stdio.h> 

EDIT3: You never tell the user that "done" ends the program. Probably should.


Also, what happens if the user types something that isn't add/sub/done?