CODEWITHSUNDEEP
c++if-statement
b1GZZ
b1GZZ

Reputation: 31

What's wrong with this if/else/else if statement?

int main(){
unsigned int fstNumb = 0, sndNumb = 0;
cout << "Choose the first number: ";
cin >> fstNumb;
cout << "\nChoose the second number: ";
cin >> sndNumb;
cout << "\nNow click \'m\' to multiply, \'a\' to add or \'d\' to divide: ";
char option = '\0';
cin >> option; cout << "\n\n";
float result;
if (option == 'm'){
    result = fstNumb * sndNumb;
    cout << result;
} 
else if (option == 'a'){
    result = fstNumb + sndNumb;
    cout << result;
}
else if (option == 'd') {
    if (fstNumb || sndNumb == 0)
        cout << "Cannot divide with 0 :/";
    else {
        cout << "You want the " << fstNumb << " or " << sndNumb << " to be divided?\n";
        cout << "Press 1 for " << fstNumb << " or 2 for " << sndNumb;
        char option2 = '\0';
        cin >> option2;
        if (option2 == 1){
            cout << "\nYou chose " << fstNumb;
            cout << "\nWanna divide it by how much?: ";
            unsigned short division;
            cin >> division;
            if (division == 0){
                cout << "\nCannot divide by 0!";
            }
            else{
                result = fstNumb / division;
            }
        }
        else if (option2 == 2){
            cout << "\nYou chose " << sndNumb;
            cout << "\nWanna divide it by how much?: ";
            unsigned short division;
            cin >> division;
            result = sndNumb / division;
        }
        else
            cout << "You must choose one of those 2 numbers!\n";
    }
}
else
    cout << "That's none of the letters I asked you.\n";

}

That if (fstNumb || sndNumb == 0) always displays even when none of the integers are 0, what's the problem?
Note that I'm not using boolean variables, but that shouldn't be a problem I guess.

Upvotes: 0

Views: 202

Answers (4)

Mukit09
Mukit09

Reputation: 3399

if (fstNumb || sndNumb == 0)

is as same as 

if (fstNumb != 0 || sndNumb == 0)

Change this part to (if you don't expect answer as 0),

if (fstNumb == 0 || sndNumb == 0)

But if there is no problem to get 0 as answer,

if ( sndNumb == 0)

Upvotes: 2

Ali Akber
Ali Akber

Reputation: 3800

Change condition if (fstNumb || sndNumb == 0) to if (sndNumb == 0)
Because first number can be 0.

Input  : 0 12 
Answer : 0

Upvotes: 0

elixenide
elixenide

Reputation: 44851

Short answer: Your logic is incorrect. if (fstNumb || sndNumb == 0) is the same as if ( (fstNumb != 0) || (sndNumb == 0) ), but you want if (fstNumb == 0 || sndNumb == 0). Change it to the latter and it will work as expected.

To explain why "Cannot divide with 0 :/" displays even if neither fstNumb nor sndNumb is 0:

If fstNumb is nonzero, then it evaluates as true when treated as a boolean (zero is false; everything else is true). || has lower precedence than ==, so the whole expression evaluates to fstNumb || (sndNumb == 0). When fstNumb != 0, that expression is the same as true || (sndNumb == 0), which is always true.

Upvotes: 1

bakkal
bakkal

Reputation: 55448

if (fstNumb || sndNumb == 0) is not the same thing as if (fstNumb == 0 || sndNumb == 0)

Upvotes: 5

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