user10349924
Reputation:
Calculator output wrong answer
import math
def findNextOpr(txt):
if len(txt)<=0 or not isinstance(txt,str):
return "type error: findNextOpr"
# --- YOU CODE STARTS HERE
if type(txt) == str:
opr_list = ["+", "-", "*", "/", '^']
for i in range(len(txt)):
if txt[i] in opr_list:
return(i)
return(-1)
# --- CODE ENDS HERE
def isNumber(txt):
if not isinstance(txt, str):
return "type error: isNumber"
if len(txt)==0:
return False
# --- YOU CODE STARTS HERE
if type(txt) == str:
try:
float(txt)
return True
except ValueError:
return False
def getNextNumber(expr, pos):
if len(expr)==0 or not isinstance(expr, str) or pos<0 or pos>=len(expr) or not isinstance(pos, int):
return None, None, "type error: getNextNumber"
# --- YOU CODE STARTS HERE
txt = expr[pos:]
oprPos = findNextOpr(txt)
if oprPos != -1:
if isNumber(txt[:oprPos]) == True:
return float(txt[:oprPos]), txt[oprPos], oprPos+pos
else:
return None, txt[oprPos], oprPos+pos
else:
if isNumber(txt):
return float(txt), None, None
else:
return None,None,None
# --- CODE ENDS HERE
def exeOpr(num1, opr, num2):
#This function is just an utility function for calculator(expr). It is skipping type check
if opr=="+":
return num1+num2
elif opr=="-":
return num1-num2
elif opr=="*":
return num1*num2
elif opr=="/":
return num1/num2
elif opr=="^":
return num1**num2
else:
return "error in exeOpr"
def calculator(expr):
if len(expr)<=0 or not isinstance(expr,str):
return "error"
expr = expr.strip()
if expr[0]!="-":
newNumber, newOpr, oprPos = getNextNumber(expr, 0)
else:
newNumber, newOpr, oprPos = getNextNumber(expr, 1)
newNumber *= -1
if newNumber is None:
return "error"
elif newOpr is None:
return newNumber
elif newOpr=="+" or newOpr=="-":
mode="add"
addResult=newNumber
mulResult=None
expResult=None
elif newOpr=="*" or newOpr=="/":
mode="mul"
addResult=0
mulResult=newNumber
expResult=None
elif newOpr=="^":
mode="exp"
expResult=newNumber
addResult=0
mulResult=None
pos=oprPos+1
opr=newOpr
oldopr=None
while True:
newNumber, newOpr, oprPos = getNextNumber(expr, pos)
if newNumber is None:
return "input error: line B in calculator"
elif newOpr is None:
if mode=='add':
if opr=='*':
return exeOpr(addResult, oldopr, mulResult*newNumber)
elif opr=='/':
return exeOpr(addResult, oldopr, mulResult/newNumber)
else:
return exeOpr(addResult, opr, newNumber)
elif mode=='mul':
if expResult==None:
expResult=0
if mulResult==None:
mulResult=0
return addResult + exeOpr(mulResult, opr, newNumber)
elif mode=="exp":
if expResult<0:
expResult=exeOpr(expResult,opr,newNumber)
if expResult>0:
expResult=-1*expResult
else:
expResult=exeOpr(expResult,opr,newNumber)
if mulResult!=0 and (oldopr=='*' or oldopr=='/'):
mulResult=exeOpr(mulResult,oldopr,expResult)
expResult=0
elif newOpr=='+' or newOpr=='-':
if expResult==None:
expResult=0
if mulResult==None:
mulResult=0
if mode=='add':
addResult = exeOpr(addResult, opr, newNumber)
mulResult = 0
expResult= 0
elif mode=='mul':
addResult += exeOpr(mulResult, opr, newNumber)
mulResult = 0
expResult= 0
elif mode=='exp':
if expResult<0:
expResult=exeOpr(expResult,opr,newNumber)
if expResult>0:
expResult=-1*expResult
addResult+=expResult
else:
addResult+=exeOpr(expResult,opr,newNumber)
if oldopr=='*' or oldopr=='/':
expResult=exeOpr(expResult,opr,newNumber)
mulResult=exeOpr(mulResult,oldopr,expResult)
addResult+=mulResult
mulResult = 0
expResult = 0
mode='add'
elif newOpr=="*" or newOpr=="/":
if mode=='add':
if opr=='-':
oldopr='-'
mulResult = newNumber
elif opr=='+':
#print('here1')
oldopr='+'
mulResult = newNumber
mode='mul'
else:
mulResult = newNumber
elif mode=='mul':
mulResult = exeOpr(mulResult, opr, newNumber)
elif mode=='exp':
if expResult<0:
expResult=exeOpr(expResult,opr,newNumber)
if expResult>0:
expResult=-1*expResult
else:
expResult=exeOpr(expResult,opr,newNumber)
if mulResult !=0 and (oldopr=='*' or oldopr=='/'):
mulResult=exeOpr(mulResult,oldopr,expResult)
expResult=0
else:
mulResult=expResult
expResult=0
mode='mul'
elif newOpr=='^':
if mode=='add':
if expResult==None:
expResult=0
if mulResult==None:
mulResult=0
if opr=='-':
expResult = -newNumber
else:
expResult = newNumber
oldopr=opr
elif mode=='mul':
expResult=newNumber
oldopr=opr
mode='exp'
if oprPos==None:
break
pos=oprPos + 1
opr=newOpr
if mulResult== None:
mulResult=0
if expResult==None:
expResult=0
return addResult+mulResult+expResult
Above is my code for a functional calculator no errors at all but when I run the code and try calculator('-5 + 60 / 3^3 * 4 - 2 * 4^2') I get 35.888888888888886 but the answer should be -28.11111111111111 Is there a mistake someone in my code that I cannot find? I think it might be in the calculator section since everything else works perfectly fine with tests but I just can't find where.
I was told that one way to solve in class was that maybe using a node/stack class might help but is there any other solution than creating another class
Upvotes: 1
Views: 117
Answers (1)
sal
Reputation: 3593
In the calculator big loop, when opr is -, you forgot to change the sign of mulResult.
In order to debug it, I added a print statement to the exeOpr function, so that we could see what the calculator is doing at each step. Then it was easy to determine by looking at the partial results.
The full new code is like this:
import math
def findNextOpr(txt):
if len(txt) <= 0 or not isinstance(txt, str):
return "type error: findNextOpr"
# --- YOU CODE STARTS HERE
if type(txt) == str:
opr_list = ["+", "-", "*", "/", '^']
for i in range(len(txt)):
if txt[i] in opr_list:
return (i)
return (-1)
# --- CODE ENDS HERE
def isNumber(txt):
if not isinstance(txt, str):
return "type error: isNumber"
if len(txt) == 0:
return False
# --- YOU CODE STARTS HERE
if type(txt) == str:
try:
float(txt)
return True
except ValueError:
return False
def getNextNumber(expr, pos):
if len(expr) == 0 or not isinstance(expr, str) or pos < 0 or pos >= len(expr) or not isinstance(pos, int):
return None, None, "type error: getNextNumber"
# --- YOU CODE STARTS HERE
txt = expr[pos:]
oprPos = findNextOpr(txt)
if oprPos != -1:
if isNumber(txt[:oprPos]):
return float(txt[:oprPos]), txt[oprPos], oprPos + pos
else:
return None, txt[oprPos], oprPos + pos
else:
if isNumber(txt):
return float(txt), None, None
else:
return None, None, None
# --- CODE ENDS HERE
def exeOpr(num1, opr, num2):
# This function is just an utility function for calculator(expr). It is skipping type check
print("%s %s %s" % (num1, opr, num2)) # <==== DEBUGGING PRINT
if opr == "+":
return num1 + num2
elif opr == "-":
return num1 - num2
elif opr == "*":
return num1 * num2
elif opr == "/":
return num1 / num2
elif opr == "^":
return num1 ** num2
else:
return "error in exeOpr"
def calculator(expr):
if len(expr) <= 0 or not isinstance(expr, str):
return "error"
expr = expr.strip()
if expr[0] != "-":
newNumber, newOpr, oprPos = getNextNumber(expr, 0)
else:
newNumber, newOpr, oprPos = getNextNumber(expr, 1)
newNumber *= -1
if newNumber is None:
return "error"
elif newOpr is None:
return newNumber
elif newOpr == "+" or newOpr == "-":
mode = "add"
addResult = newNumber
mulResult = None
expResult = None
elif newOpr == "*" or newOpr == "/":
mode = "mul"
addResult = 0
mulResult = newNumber
expResult = None
elif newOpr == "^":
mode = "exp"
expResult = newNumber
addResult = 0
mulResult = None
pos = oprPos + 1
opr = newOpr
oldopr = None
while True:
newNumber, newOpr, oprPos = getNextNumber(expr, pos)
if newNumber is None:
return "input error: line B in calculator"
elif newOpr is None:
if mode == 'add':
if opr == '*':
return exeOpr(addResult, oldopr, mulResult * newNumber)
elif opr == '/':
return exeOpr(addResult, oldopr, mulResult / newNumber)
else:
return exeOpr(addResult, opr, newNumber)
elif mode == 'mul':
if expResult == None:
expResult = 0
if mulResult == None:
mulResult = 0
return addResult + exeOpr(mulResult, opr, newNumber)
elif mode == "exp":
if expResult < 0:
expResult = exeOpr(expResult, opr, newNumber)
if expResult > 0:
expResult = -1 * expResult
else:
expResult = exeOpr(expResult, opr, newNumber)
if mulResult != 0 and (oldopr == '*' or oldopr == '/'):
mulResult = exeOpr(mulResult, oldopr, expResult)
expResult = 0
elif newOpr == '+' or newOpr == '-':
if expResult == None:
expResult = 0
if mulResult == None:
mulResult = 0
if mode == 'add':
addResult = exeOpr(addResult, opr, newNumber)
mulResult = 0
expResult = 0
elif mode == 'mul':
addResult += exeOpr(mulResult, opr, newNumber)
mulResult = 0
expResult = 0
elif mode == 'exp':
if expResult < 0:
expResult = exeOpr(expResult, opr, newNumber)
if expResult > 0:
expResult = -1 * expResult
addResult += expResult
else:
addResult += exeOpr(expResult, opr, newNumber)
if oldopr == '*' or oldopr == '/':
expResult = exeOpr(expResult, opr, newNumber)
mulResult = exeOpr(mulResult, oldopr, expResult)
addResult += mulResult
mulResult = 0
expResult = 0
mode = 'add'
elif newOpr == "*" or newOpr == "/":
if mode == 'add':
if opr == '-':
oldopr = '-'
mulResult = -newNumber # <====== THIS IS THE PLACE I CHANGED
elif opr == '+':
# print('here1')
oldopr = '+'
mulResult = newNumber
mode = 'mul'
else:
mulResult = newNumber
elif mode == 'mul':
mulResult = exeOpr(mulResult, opr, newNumber)
elif mode == 'exp':
if expResult < 0:
expResult = exeOpr(expResult, opr, newNumber)
if expResult > 0:
expResult = -1 * expResult
else:
expResult = exeOpr(expResult, opr, newNumber)
if mulResult != 0 and (oldopr == '*' or oldopr == '/'):
mulResult = exeOpr(mulResult, oldopr, expResult)
expResult = 0
else:
mulResult = expResult
expResult = 0
mode = 'mul'
elif newOpr == '^':
if mode == 'add':
if expResult == None:
expResult = 0
if mulResult == None:
mulResult = 0
if opr == '-':
expResult = -newNumber
else:
expResult = newNumber
oldopr = opr
elif mode == 'mul':
expResult = newNumber
oldopr = opr
mode = 'exp'
if oprPos == None:
break
pos = oprPos + 1
opr = newOpr
if mulResult == None:
mulResult = 0
if expResult == None:
expResult = 0
return addResult + mulResult + expResult
x = calculator('-5 + 60 / 3^3 * 4 - 2 * 4^2')
print(x)
Upvotes: 1
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