C++ problems with cin, cout and the if statement.

Question

Hey guys, I am pretty new to this but thought this would be the best place to start.
I am trying to make a piece of code that when the letter a is input, it will display "4x". Likewise when the letter b is input it will display "6x^2". It works perfectly when I input 'a' but for some reason whenever I input 'b' it displays "No Output". All help would be greatly appreciated! I've tried doing it 2 ways, but neither work.

#include <iostream>
#include <cctype>
#include <cmath>
using namespace std;

int main()
{
char a;
char b;

cin >> a;
cin >> b;
if (a == 'a'|| a == 'A')
cout << "4x";
else if (b == 'b'|| b == 'B')
cout << "6x^2";

}

Method 2 :

#include <iostream>
#include <cctype>
#include <cmath>
using namespace std;

int main()
{
char a;
cin >> a;
if (a == 'a'|| a == 'A')
cout << "4x";

char b;
cin >> b;
if (b == 'b'|| b == 'B')
cout << "6x^2";

}

Answer 1

You only need one variable to achieve what you are doing.

char a;
cin >> a;

if (a == 'a' || a == 'A') cout << "4x";
else if (a == 'b' || a == 'B') cout << "6x^2";

The reason why your examples are not working for b is because your program expects the user to input to both variable a and b, but only received one input.

Answer 2

Your code works, but not as you expect.
You need to input 2 chars, because you have 2 cin for 2 variables. And if the first is true then the 2nd will be ignored.

I guess you want something like

char input;
cin >> input;

if (input == 'a' || input == 'A')
cout << "4x";
else if (input == 'b' || input == 'B')
cout << "6x^2";

Answer 3

Thank you so much Hatsy! Was banging my head off the wall trying to figure that one out! Thank you also Alex! Very helpful both of you.

Answer 4

you have typed std::<<

Answer 5

Hello everybody. I have some problems with my code. Compilator shows me that string statement cannot be used here: # include <iostream>
using namespace std;
int main()
{
string name;
cout<<"введите имя математического действия";
cin>>name;

if (name=='сложение')

{

float a,b,c;
cout<<"1 число=";
cin>>a;
cout<<"2 число=";
cin>>b;
c=a+b;
std::<<cout"a+b="<<c<<std::endl;

}

if (name=='вычитание')

{

float a,b,c;
cout<<"1 число=";
cin>>a;
cout<<"2 число=";
cin>>b;
c=a-b;
std::cout<<"a-b="<<c<<std::endl;

}

if (name=='умножение')

{
float a,b,c;
cout<<"1 число=";
cin>>a;
cout<<"2 число=";
cin>>b;
c=a*b;
std::cout<<"a*b="<<c<<std::endl;

}

}

Answer 6

Yeah, cout is used as "std::cout << 'text'".
Also, not sure, but usually when working with string types,
#include <string>