Converting binary to decimal only using basic functions len(), ord(), print(), etc












0














I'm trying to create a scientific calculator for an assignment. I'm looking for a bit of help with python syntax, and I think my design and pseudo code are doing well, but for whatever reason python isn't having any of my syntactical issues. Here is the code I have for converting binary to decimal.



I need the code to reprompt when the input is invalid, but when it does reprompt, it gets stuck in a loop of reprompting and won't give me any way out.



def bintodec(var):
power = (len(var) + 1)
value = ' '
while True:

var = input('Give a number to convert from binary to decimal: ')
for x in range(len(var)):

if (ord(var[x]) == 49):
power -= 1
value += x * (2 ** power)

if (ord(var[x]) == 48):
power -= 1
value += x * (2 ** power)

if power == -1:
break

else:
boo = True

return value


Any help is greatly appreciated!










share|improve this question
























  • The break statement only exits the innermost loop. See the duplicate (link above) for ways to refactor your code to break out of the outer loop.
    – Jim Stewart
    Nov 12 '18 at 1:08






  • 1




    Do you actually have to use ord here... The code would be much more readable if you just do for x in var: if x == '0'.... etc... Also you're doing the same operations for 0 and 1 so you might as well put those in the same block
    – Jon Clements
    Nov 12 '18 at 1:09












  • The answers to the question Asking the user for input until they give a valid response should help with getting input from the user.
    – martineau
    Nov 12 '18 at 2:32


















0














I'm trying to create a scientific calculator for an assignment. I'm looking for a bit of help with python syntax, and I think my design and pseudo code are doing well, but for whatever reason python isn't having any of my syntactical issues. Here is the code I have for converting binary to decimal.



I need the code to reprompt when the input is invalid, but when it does reprompt, it gets stuck in a loop of reprompting and won't give me any way out.



def bintodec(var):
power = (len(var) + 1)
value = ' '
while True:

var = input('Give a number to convert from binary to decimal: ')
for x in range(len(var)):

if (ord(var[x]) == 49):
power -= 1
value += x * (2 ** power)

if (ord(var[x]) == 48):
power -= 1
value += x * (2 ** power)

if power == -1:
break

else:
boo = True

return value


Any help is greatly appreciated!










share|improve this question
























  • The break statement only exits the innermost loop. See the duplicate (link above) for ways to refactor your code to break out of the outer loop.
    – Jim Stewart
    Nov 12 '18 at 1:08






  • 1




    Do you actually have to use ord here... The code would be much more readable if you just do for x in var: if x == '0'.... etc... Also you're doing the same operations for 0 and 1 so you might as well put those in the same block
    – Jon Clements
    Nov 12 '18 at 1:09












  • The answers to the question Asking the user for input until they give a valid response should help with getting input from the user.
    – martineau
    Nov 12 '18 at 2:32
















0












0








0







I'm trying to create a scientific calculator for an assignment. I'm looking for a bit of help with python syntax, and I think my design and pseudo code are doing well, but for whatever reason python isn't having any of my syntactical issues. Here is the code I have for converting binary to decimal.



I need the code to reprompt when the input is invalid, but when it does reprompt, it gets stuck in a loop of reprompting and won't give me any way out.



def bintodec(var):
power = (len(var) + 1)
value = ' '
while True:

var = input('Give a number to convert from binary to decimal: ')
for x in range(len(var)):

if (ord(var[x]) == 49):
power -= 1
value += x * (2 ** power)

if (ord(var[x]) == 48):
power -= 1
value += x * (2 ** power)

if power == -1:
break

else:
boo = True

return value


Any help is greatly appreciated!










share|improve this question















I'm trying to create a scientific calculator for an assignment. I'm looking for a bit of help with python syntax, and I think my design and pseudo code are doing well, but for whatever reason python isn't having any of my syntactical issues. Here is the code I have for converting binary to decimal.



I need the code to reprompt when the input is invalid, but when it does reprompt, it gets stuck in a loop of reprompting and won't give me any way out.



def bintodec(var):
power = (len(var) + 1)
value = ' '
while True:

var = input('Give a number to convert from binary to decimal: ')
for x in range(len(var)):

if (ord(var[x]) == 49):
power -= 1
value += x * (2 ** power)

if (ord(var[x]) == 48):
power -= 1
value += x * (2 ** power)

if power == -1:
break

else:
boo = True

return value


Any help is greatly appreciated!







python binary decimal






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 12 '18 at 1:13









cricket_007

79.3k1142109




79.3k1142109










asked Nov 12 '18 at 1:05









Jay F.

31




31












  • The break statement only exits the innermost loop. See the duplicate (link above) for ways to refactor your code to break out of the outer loop.
    – Jim Stewart
    Nov 12 '18 at 1:08






  • 1




    Do you actually have to use ord here... The code would be much more readable if you just do for x in var: if x == '0'.... etc... Also you're doing the same operations for 0 and 1 so you might as well put those in the same block
    – Jon Clements
    Nov 12 '18 at 1:09












  • The answers to the question Asking the user for input until they give a valid response should help with getting input from the user.
    – martineau
    Nov 12 '18 at 2:32




















  • The break statement only exits the innermost loop. See the duplicate (link above) for ways to refactor your code to break out of the outer loop.
    – Jim Stewart
    Nov 12 '18 at 1:08






  • 1




    Do you actually have to use ord here... The code would be much more readable if you just do for x in var: if x == '0'.... etc... Also you're doing the same operations for 0 and 1 so you might as well put those in the same block
    – Jon Clements
    Nov 12 '18 at 1:09












  • The answers to the question Asking the user for input until they give a valid response should help with getting input from the user.
    – martineau
    Nov 12 '18 at 2:32


















The break statement only exits the innermost loop. See the duplicate (link above) for ways to refactor your code to break out of the outer loop.
– Jim Stewart
Nov 12 '18 at 1:08




The break statement only exits the innermost loop. See the duplicate (link above) for ways to refactor your code to break out of the outer loop.
– Jim Stewart
Nov 12 '18 at 1:08




1




1




Do you actually have to use ord here... The code would be much more readable if you just do for x in var: if x == '0'.... etc... Also you're doing the same operations for 0 and 1 so you might as well put those in the same block
– Jon Clements
Nov 12 '18 at 1:09






Do you actually have to use ord here... The code would be much more readable if you just do for x in var: if x == '0'.... etc... Also you're doing the same operations for 0 and 1 so you might as well put those in the same block
– Jon Clements
Nov 12 '18 at 1:09














The answers to the question Asking the user for input until they give a valid response should help with getting input from the user.
– martineau
Nov 12 '18 at 2:32






The answers to the question Asking the user for input until they give a valid response should help with getting input from the user.
– martineau
Nov 12 '18 at 2:32














1 Answer
1






active

oldest

votes


















0














This is pretty classic. Reading in a base is easier than writing in one.





def bintodec(var):
assert set(var) <= set("01") # Just check that we only have 0s and 1s
assert isinstance(var, str) # Checks that var is a string

result = 0
for character in var: # character will be each character of var, from left to rigth
digitvalue = ord(character) - ord("0")
result *= 2
result += digitvalue

return result


Ok, how does it work ?



Well, it reads the value from left to right. digitvalue will contain 1 or 0. For each digit we read, if it is 0, there is nothing to add the result (so result += digitvalue adds indeed 0), but we still need take into account that there is one more 0 at the end of the number.



Now, in base 10, adding a zero to the end makes a number 10 times as big. This is the same in base 2. Adding a zero at the end makes a number twice as big. This is why we multiply it by 2.



Finally, if digitvalue is 1 instead of 0, we need to add 1 to the number and result += digitvalue does it.



Note: Just for things to be clear, the two for loops below are equivalent.



for character in var:
pass # pass does nothing

for i in range(len(var)):
character = var[i]
pass





@JayF.:



Is there any way to reprompt without using assert?




I suppose you want to reprompt if the input is incorrect. You need to use a loop for that:



while True:
var = input()
if set(var) <= set("01"):
print(bintodec(var))
break # Remove this `break` statement if you want to reprompt forever
else:
# print("The input must consist of only 0s and 1s.")
pass # `pass` does nothing.


If you leave the asserts in the bintodec function, it can be done in a more pythonic way, using exception handling:



while True:
var = input()
try:
print(bintodec(var))
break
except AssertionError:
print("The input must consist of only 0s and 1s.")





share|improve this answer























  • Is there any way to reprompt without using assert? Thanks for your help!
    – Jay F.
    Nov 12 '18 at 21:20










  • If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
    – Mathieu CAROFF
    Nov 16 '18 at 20:06











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









0














This is pretty classic. Reading in a base is easier than writing in one.





def bintodec(var):
assert set(var) <= set("01") # Just check that we only have 0s and 1s
assert isinstance(var, str) # Checks that var is a string

result = 0
for character in var: # character will be each character of var, from left to rigth
digitvalue = ord(character) - ord("0")
result *= 2
result += digitvalue

return result


Ok, how does it work ?



Well, it reads the value from left to right. digitvalue will contain 1 or 0. For each digit we read, if it is 0, there is nothing to add the result (so result += digitvalue adds indeed 0), but we still need take into account that there is one more 0 at the end of the number.



Now, in base 10, adding a zero to the end makes a number 10 times as big. This is the same in base 2. Adding a zero at the end makes a number twice as big. This is why we multiply it by 2.



Finally, if digitvalue is 1 instead of 0, we need to add 1 to the number and result += digitvalue does it.



Note: Just for things to be clear, the two for loops below are equivalent.



for character in var:
pass # pass does nothing

for i in range(len(var)):
character = var[i]
pass





@JayF.:



Is there any way to reprompt without using assert?




I suppose you want to reprompt if the input is incorrect. You need to use a loop for that:



while True:
var = input()
if set(var) <= set("01"):
print(bintodec(var))
break # Remove this `break` statement if you want to reprompt forever
else:
# print("The input must consist of only 0s and 1s.")
pass # `pass` does nothing.


If you leave the asserts in the bintodec function, it can be done in a more pythonic way, using exception handling:



while True:
var = input()
try:
print(bintodec(var))
break
except AssertionError:
print("The input must consist of only 0s and 1s.")





share|improve this answer























  • Is there any way to reprompt without using assert? Thanks for your help!
    – Jay F.
    Nov 12 '18 at 21:20










  • If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
    – Mathieu CAROFF
    Nov 16 '18 at 20:06
















0














This is pretty classic. Reading in a base is easier than writing in one.





def bintodec(var):
assert set(var) <= set("01") # Just check that we only have 0s and 1s
assert isinstance(var, str) # Checks that var is a string

result = 0
for character in var: # character will be each character of var, from left to rigth
digitvalue = ord(character) - ord("0")
result *= 2
result += digitvalue

return result


Ok, how does it work ?



Well, it reads the value from left to right. digitvalue will contain 1 or 0. For each digit we read, if it is 0, there is nothing to add the result (so result += digitvalue adds indeed 0), but we still need take into account that there is one more 0 at the end of the number.



Now, in base 10, adding a zero to the end makes a number 10 times as big. This is the same in base 2. Adding a zero at the end makes a number twice as big. This is why we multiply it by 2.



Finally, if digitvalue is 1 instead of 0, we need to add 1 to the number and result += digitvalue does it.



Note: Just for things to be clear, the two for loops below are equivalent.



for character in var:
pass # pass does nothing

for i in range(len(var)):
character = var[i]
pass





@JayF.:



Is there any way to reprompt without using assert?




I suppose you want to reprompt if the input is incorrect. You need to use a loop for that:



while True:
var = input()
if set(var) <= set("01"):
print(bintodec(var))
break # Remove this `break` statement if you want to reprompt forever
else:
# print("The input must consist of only 0s and 1s.")
pass # `pass` does nothing.


If you leave the asserts in the bintodec function, it can be done in a more pythonic way, using exception handling:



while True:
var = input()
try:
print(bintodec(var))
break
except AssertionError:
print("The input must consist of only 0s and 1s.")





share|improve this answer























  • Is there any way to reprompt without using assert? Thanks for your help!
    – Jay F.
    Nov 12 '18 at 21:20










  • If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
    – Mathieu CAROFF
    Nov 16 '18 at 20:06














0












0








0






This is pretty classic. Reading in a base is easier than writing in one.





def bintodec(var):
assert set(var) <= set("01") # Just check that we only have 0s and 1s
assert isinstance(var, str) # Checks that var is a string

result = 0
for character in var: # character will be each character of var, from left to rigth
digitvalue = ord(character) - ord("0")
result *= 2
result += digitvalue

return result


Ok, how does it work ?



Well, it reads the value from left to right. digitvalue will contain 1 or 0. For each digit we read, if it is 0, there is nothing to add the result (so result += digitvalue adds indeed 0), but we still need take into account that there is one more 0 at the end of the number.



Now, in base 10, adding a zero to the end makes a number 10 times as big. This is the same in base 2. Adding a zero at the end makes a number twice as big. This is why we multiply it by 2.



Finally, if digitvalue is 1 instead of 0, we need to add 1 to the number and result += digitvalue does it.



Note: Just for things to be clear, the two for loops below are equivalent.



for character in var:
pass # pass does nothing

for i in range(len(var)):
character = var[i]
pass





@JayF.:



Is there any way to reprompt without using assert?




I suppose you want to reprompt if the input is incorrect. You need to use a loop for that:



while True:
var = input()
if set(var) <= set("01"):
print(bintodec(var))
break # Remove this `break` statement if you want to reprompt forever
else:
# print("The input must consist of only 0s and 1s.")
pass # `pass` does nothing.


If you leave the asserts in the bintodec function, it can be done in a more pythonic way, using exception handling:



while True:
var = input()
try:
print(bintodec(var))
break
except AssertionError:
print("The input must consist of only 0s and 1s.")





share|improve this answer














This is pretty classic. Reading in a base is easier than writing in one.





def bintodec(var):
assert set(var) <= set("01") # Just check that we only have 0s and 1s
assert isinstance(var, str) # Checks that var is a string

result = 0
for character in var: # character will be each character of var, from left to rigth
digitvalue = ord(character) - ord("0")
result *= 2
result += digitvalue

return result


Ok, how does it work ?



Well, it reads the value from left to right. digitvalue will contain 1 or 0. For each digit we read, if it is 0, there is nothing to add the result (so result += digitvalue adds indeed 0), but we still need take into account that there is one more 0 at the end of the number.



Now, in base 10, adding a zero to the end makes a number 10 times as big. This is the same in base 2. Adding a zero at the end makes a number twice as big. This is why we multiply it by 2.



Finally, if digitvalue is 1 instead of 0, we need to add 1 to the number and result += digitvalue does it.



Note: Just for things to be clear, the two for loops below are equivalent.



for character in var:
pass # pass does nothing

for i in range(len(var)):
character = var[i]
pass





@JayF.:



Is there any way to reprompt without using assert?




I suppose you want to reprompt if the input is incorrect. You need to use a loop for that:



while True:
var = input()
if set(var) <= set("01"):
print(bintodec(var))
break # Remove this `break` statement if you want to reprompt forever
else:
# print("The input must consist of only 0s and 1s.")
pass # `pass` does nothing.


If you leave the asserts in the bintodec function, it can be done in a more pythonic way, using exception handling:



while True:
var = input()
try:
print(bintodec(var))
break
except AssertionError:
print("The input must consist of only 0s and 1s.")






share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 13 '18 at 13:29









loxaxs

401517




401517










answered Nov 12 '18 at 2:48









Mathieu CAROFF

3467




3467












  • Is there any way to reprompt without using assert? Thanks for your help!
    – Jay F.
    Nov 12 '18 at 21:20










  • If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
    – Mathieu CAROFF
    Nov 16 '18 at 20:06


















  • Is there any way to reprompt without using assert? Thanks for your help!
    – Jay F.
    Nov 12 '18 at 21:20










  • If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
    – Mathieu CAROFF
    Nov 16 '18 at 20:06
















Is there any way to reprompt without using assert? Thanks for your help!
– Jay F.
Nov 12 '18 at 21:20




Is there any way to reprompt without using assert? Thanks for your help!
– Jay F.
Nov 12 '18 at 21:20












If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
– Mathieu CAROFF
Nov 16 '18 at 20:06




If the answer satisfies you, you can mark it as accepted, or otherwise, append an edit to your question or interact through comments.
– Mathieu CAROFF
Nov 16 '18 at 20:06


















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