Thread: Password

It's not an error, it's a way for the computer to handle high precision decimal numbers. Internally the number is stored in such a way that it can be used for either very large numbers (many places to the left of the decimal) or very small numbers (many places to the right of the decimal).

Basically, the machine represents the numbers in exponential format for floats (one bit for the sign, 7-11 bits (depending on float or double) for another part, and the remaining bits for the mantissa) versus using the binary nature of storage for ints.

Whereas ints are represented like such:
00000000 = zero
00000010 = two
00000100 = four
00000101 = five
etc.

A float is stored with a very different method (rather complex and can vary from compiler to compiler) in such a way that while it is not exact, it holds a much broader range. Internally it looks more like

0 0100101 010010100101010010101000

if you were to break up the bits into the different parts. (some compilers store them in different orders, but the result is the same)

Most of this is academic, unless you want to get into compiler design or very advanced tricks and stuff. The main thing to remember is this: == with floats or doubles is most likely to be false, no matter what the values of the numbers, while != is most likely to be true with floats and doubles, no matter what the numbers.

Like any tool, you use them when appropriate and remember how to use them properly. floats and doubles are useful for representing money, temperature, and anything else that might have a fractional part, ints are useful for most other things.

for representing money, temperature,

Why?
Due to the inaccuracy of floating-point types, isn't it better to simply use a larger integer type and divide by a set amount to get the real answer?

i.e.

Code:

float fNumber = 150.25;//normal, but possibly inaccurate
long long lNumber = 150250000;//just divide this by 6 and you can get the real value.  you can use == on the 
long longs and just cast them to float and divide by 6 for output

It was just an example; you can make it whatever you want (as long as it will fit in the variable).

I use itoa a lot, and I really don't like all the compiler warnings I get.

My solution is just to rewrite it and call it my_itoa

i Just thought i'd take a shot at the initial problem:

Code:

#include <iostream>

using namespace std;

int main()
{
     char password[20];
     cout<<"Enter Password: ";
     cin.getline(password, 20);
     if(strcmp(password, "PASSWORD")==0)  // your password in ""
     {
          cout<<"Correct!";
          .......Whatever you want it to do.....
     }
     else{
          cout<<"Wrong!";
     }
     return 0;
}

i think the (strcmp) thing is right, im new to this too.

As explained before, this is terrible protection because you can view it in a hex editor or disassembler (hell, even notepad!)