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post Program acting weird...

ccsdude (6)
Hello I am new to C++ and I have been experimenting and one program I wrote acts weird... Let me post the code and then I'll explain what is happening.

I apologize for any words misspelled english is my second language, most of the identifiers for the variables or other things that the name doesn't matter are named in spanish

#include <iostream>
#include <string>
using namespace std;

string unidad;

float calcular(float a, float b, float c) {
a = a*12;
b = b*2;
if (c<a, c<b) { unidad = "1 dozen"; return (c); }
else if (b<a, b<c) { unidad = "half dozen"; return (b); }
else if (a<b, a<c) { unidad = "12 units"; return (a); }
else (c==a, c==b); { cout << "everything cost the same, buy 1 dozen for comfort" << "\n"; }
}

int main() {
float precio1, precio6, precio12, result;
cout << "price 1 unit, half dozen, 1 dozen"; cin >> precio1 >> precio6 >> precio12;
result = calcular(precio1, precio6, precio12);
cout << "it is recomended to buy: " << unidad << endl << "it will cost: " << result << endl;

system ("pause > nul");
}

The program is supposed to calculate which price is lower and tell the person what is the best option on how to buy.

The weird thing is that if I put that a unit value is 1 to make it 12, I put the half a dozen value to 7 to make it 14 and the dozen price to 13 it chosses the dozen instead of the unit, but if change the price of half a dozen to 6.5 to make it 13 if chosses the unit. If I maintain the price of the half a dozen to 6.5 to make it 13 and I change the price of the dozen to 14 it chosses the half dozen although the unit price is 1 to make it 12.
Zhuge (2205)
You cannot use commas in an if statement in C++ as far as I know (I'm suprised your compiler didn't throw an error). You probably want to use the "logical and" operator, which is two ampersands (&&).

Example:
if(c<a && c<b)
This will be true is c is less than a AND c is less than b.
ccsdude (6)
Thanks I change it and it works perfectly.

Don't know why it didn't throw an error I am using Dev C++.
kadyssss (6)
It is not an error.

Just a silly mistake your make.

U must pay more attention to it in futher.

Check u program carefully and gain a clear idea of C++ Language.
firedraco (4744)
Um, if it is a mistake...it's an error to the compiler...>.>

Although maybe it threw a warning instead, but I don't know how it would run with the comma there...
Faldrax (324)
The comma operator is a legal way of putting multiple expressions in the place of a single expression.
The 'normal' place for it is in a for loop,
EG
1
2
3
4
 
For (int a=3, int b=4; a<5; a++, b--)
{
  //do something with 2 changing values
}

The value of such an expression is the value of the last expression in the series, so in your code what you had effecivly written was
1
2
3
4
5
 
if (c<b) { unidad = "1 dozen"; return (c); }
else if (b<c) { unidad = "half dozen"; return (b); }
else if (a<c) { unidad = "12 units"; return (a); }
else (c==a, c==b); 
{ cout << "everything cost the same, buy 1 dozen for comfort" << "\n"; }

That's one of the things about C++, you can combine syntax in very odd ways - sometimes there are good reasons to do so, but often it just conceals errors and confuses you:-)
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