Binary to Decimal (Easy, read first before getting angry)

[modesto916]

Hi,

I know that there are many topics about this, but, i read a lot of them, and no one solved my problem.

I doing some exercises of the book "Deitel How to Program, 5", and in the exercise 4.27 i need to write a program that get a binary integer from user, then print it in decimal, but i can only use the programming techniques that i have learned in the book, here is a shell script that i have written to do it, if i write this in c++ i will be done.

#!/bin/sh

binary=$1
numberOfChars="`echo $binary |wc -c`"
counter="1"
decimal="0"

while [ $counter -lt $numberOfChars ]
do

   if [ `echo $binary |cut -c $counter` -lt 0 ] || [ `echo $binary |cut -c $counter` -gt 1 ]
      then

         echo "A Binary number contains only 0s e 1s."

         exit 0

   fi

   decimal=`expr $decimal \* 2 + \`echo $binary |cut -c $counter\` `

   counter=`expr $counter + 1`

done

echo "Decimal: $decimal"

exit 0

The problem is that in C++ i don't know how can i use something like "cut", there is a hint in the book, saying that i can use module and division operators to get the digits, but i only know how to do it with a predetermined number of digits.

Obs: Please, i cannot use "for", and i can only use the iostream and string libs.

[Ancient Dragon]

>>i don't know how can i use something like "cut",
There is no such term.

It's pretty easy to get the digits

int x = 123;
int digit;
while(x > 0)
{
   digit = x % 10;
   x /= 10;
}

[gerard4143]

I'm a little confuse...Do you want a program that will take an inputted binary number and then produce its decimal equivalent?

e.g.

enter a binary number->111
ans->7

Is that what you want?

[modesto916]

I'm a little confuse...Do you want a program that will take an inputted binary number and then produce its decimal equivalent?
Yes

It's pretty easy to get the digits
Thanks, this is what i was looking for.