import re
DEF compute_mul_div (Arg):
"" " Operation multiplication and division
: Param expression: expression
: Return: the results
"""
selection = arg [0]
mch = re.search('\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*', val)
if not mch:
return
content = re.search('\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*', val).group()
if len(content.split('*'))>1:
n1, n2 = content.split('*')
value = float(n1) * float(n2)
else:
n1, n2 = content.split('/')
value = float(n1) / float(n2)
before, after = re.split('\d+\.*\d*[\*\/]+[\+\-]?\d+\.*\d*', val, 1)
new_str = "%s%s%s" % (before,value,after)
arg [0] = new_str
compute_mul_div (arg)
DEF compute_add_sub (Arg):
"" " Operation subtraction
: Param expression: expression
: Return: the results
"""
while True:
if arg[0].__contains__('+-') or arg[0].__contains__("++") or arg[0].__contains__('-+') or arg[0].__contains__("--"):
arg[0] = arg[0].replace('+-','-')
arg[0] = arg[0].replace('++','+')
arg[0] = arg[0].replace('-+','-')
arg[0] = arg[0].replace('--','+')
else:
break
if arg[0].startswith('-'):
arg[1] += 1
arg[0] = arg[0].replace('-','&')
arg[0] = arg[0].replace('+','-')
arg[0] = arg[0].replace('&','+')
arg [0] = arg [0] [1 :]
selection = arg [0]
mch = re.search('\d+\.*\d*[\+\-]{1}\d+\.*\d*', val)
if not mch:
return
content = re.search('\d+\.*\d*[\+\-]{1}\d+\.*\d*', val).group()
if len(content.split('+'))>1:
n1, n2 = content.split('+')
value = float(n1) + float(n2)
else:
n1, n2 = content.split('-')
value = float(n1) - float(n2)
before, after = re.split('\d+\.*\d*[\+\-]{1}\d+\.*\d*', val, 1)
new_str = "%s%s%s" % (before,value,after)
arg [0] = new_str
compute_add_sub(arg)
DEF Compute (expression The):
"" " Operation Math
: Param expression: expression
: Return: the results
"""
inp = [expression,0]
# Processing multiplication and division expressions
compute_mul_div (inp)
# 处理
compute_add_sub(inp)
if divmod(inp[1],2)[1] == 1:
result = float(inp[0])
result = result * -1
else:
result = float(inp[0])
return result
DEF exec_bracket (expression The):
"" " recursive processing bracket, and calculates
: Param expression: expression
: Return: final results
"" "
# If the expression has no brackets, responsible for calculating the direct call function, the expression returns the results, such as: 2 * 1-82 + 444
IF not re.search ( ' \ (([\ + \ - . \ * \ /] * \ + D \ * \ D *) 2 {,} \) ' , expression The):
Final = Compute (expression The)
return Final
# Get the first bracket contains only a digital / decimal and operators
# as:
# [ '1-2 * ((+ 60-30 (- 40.0 / 5) * (9-2 5 * / 7 + 3/99 * 3/10 * 4 * 2998 + 568/14)) - (- 4 * 3) / (16-3 * 2)) ']
# identify: (- 40.0 / 5)
= the re.search Content ( ' \ (([\ + \ - \ * \ /]. * \ + D \ * \ D *) 2 {,} \) ' , expression The) .group ()
# Split the expression, namely:
# The [ '1-2 * ((+ 60-30 (- 40.0 / 5) * (9-2 * 5/3 + 7/3 * 99/10 * 4 * 2998 + 568 / 14)) - (- 4 * 3) / (16-3 * 2)) ']
# divided further into three parts: [' 1-2 * ((+ 60-30 ((-40.0 / 5) * (9 . 5 * -2 / +. 3. 7 /. 3 * 99/10 *. 4 * 2998 + 568/14)) - (-. 4. 3 *) / (16-3 * 2)) ']
before, Nothing, After Re =. Split ( ' \ (([\ + \ - \ * \ /]. * \ + D \ * \ D *) 2 {,} \) ' , expression The,. 1 )
print 'before：',expression
content = content[1:len(content)-1]
# Computed, extracted representation (-40.0 / 5), and viable results, namely: -40.0 / 5 = -8.0
RET = Compute (Content)
print '%s=%s' %( content, ret)
# Execution result splicing, [ '1-2 * ((+ 60-30 (-8.0 * (9-2 * 5/3 + 7/3 * 99/10 * 4 * 2998 + 568/14)) - ( *. 3 -4) / (16-3 * 2)) ']
expression the = " % S% S% S " % (before, RET, After)
Print ' After: ' , expression the
Print " = " * 10, ' the calculation end time " , " = " * 10
# Looping continues parentheses next processing operation, this is an expression of the carriers have been processed, namely:
# [ '1-2 * ((+ -8.0 * 60-30 (5 * 9-2 / 3 + 7/99 * 3/10 * 4 * 2998 + 568/14)) - (- 4 * 3) / (16-3 * 2)) ']
# So the cycle of operation until the brackets no longer contains the expression
return exec_bracket (expression The)
# Use __name__ purpose:
# Only executed python index.py, the following code was executed
# if the other person to import the module, the following code does not perform
IF __name__ == " __main__ " :
# Print '*' * 20, "please calculation expression: "" 1 - 2 * ((+ 60-30 (- 40.0 / 5) * (9-2 * 5/3 + 7/99 * 3/4 * 2998 + 10 * 568/14)) - (* -4. 3) / (16-3 * 2)) ", '*' * 20 is
# INPp = '. 1 - 2 * ((+ 60-30 (- 40.0 /. 5) * (9-2. 5 * /. 7. 3 + / 99. 3 * / * 2998 +10 * 568/14. 4)) - (* -4. 3) / (16-3 * 2)) '
INPp = " 1-2 * -30 / -12 * (-20 + -3 * 200 is / -200 * -300-100) "
# INPp =" 980.0 * 1-5 "
INPp the re.sub = ( ' \ S * ' , '', inpp)
#Expression stored in the list,
the Result = exec_bracket (the INPp)
Print the Result
