In the starter code provided on the picture, there are 3 functions (partially written), you must code the empty segments so the three functions work according to the following requirements:

findNextOpr(txt) [30 pts]

• txt is a non-empty string that contains an arithmetic expression that may include numeric values, five arithmetic operators (+, -, /, * and ^) and extra spaces. An example of such expression is -4.75 * 5 - 2.01 / 3 * 7 + 2 ^ 5

• It returns the position of the leftmost operator in txt, -1 if no operator was found. findNextOpr( 356) returns -1 findNextOpr( 3 * 4 - 5 ) returns 4

txt
0	1	2	3	4	5	6	7	8	9	10
	3			*		4		-	5

isNumber(txt) [20 pts]

• txt is a non-empty string

• It returns a boolean value, True if txt is a string convertible to float, otherwise False. Note

  that -25.22222 is a string convertible to float but -22 33 and 122 ; 45 are

  not.

• An easy way to check if str to float is possible is with a try-except block

  isNumber(Hello) returns False isNumber( 2658 ) returns True isNumber( 2 8 ) returns False

getNextNumber(expr, pos) [50 pts]

returns the operator position in expr[pos:]

getNextNumber

callboolean value

isNumber

• expr is a non-empty string, pos is an integer greater than or equal to 0

• It returns 3 values:

  o 1st returned value: the next number (as float) after pos and before the next operator (If there is no single number in it, return None)

  o 2nd returned value: the next operator (If no such operator return None)

  o 3rd returned value: the next operator position (If no such operator return None)

• The next number must account for negative numbers (see examples in the doctest)

• The next operator position is its position in expr

• It MUST use the functions findNextOpr and isNumber effectively, otherwise, no

callcfindNextOpr

returns a

credit is given to this function

getNextNumber( 356, 0) returns (356.0, None, None) getNextNumber( 3 * 4 - 5 , 5) returns (4.0, '-', 8)

pos

1st returned value

3rd returned value

2nd returned value

0	1	2	3	4	5	6	7	8	9	10	11
	3			*		4		-		5

getNextNumber( 3 * 4 - 5 , 2) returns (None, '*', 4)

1st returned 2nd returned value value (None)

getNextNumber(" 3 * -4 + 5 ", 5) returns (-4.0, '+', 9)

pos

3rd returned value

0	1	2	3	4	5	6	7	8	9	10	11
	3			*		4		-		5

pos

1st returned value (-4.0)

3rd returned value

2nd returned value

0	1	2	3	4	5	6	7	8	9	10	11	12
	3			*		-	4		+		5

Testing and Debugging are important!

• - Check the first two functions individually first

• - Input some parameters and check the returned value(s)

• - Use the Python debugger discussed on Module 2 to help you debug your code

• - Use Pythons unittest module to run extensive cases on your code to ensure full credit

  Deliverables:

  Include all the functions in your script named HW3.py and submit it to the HW3 Gradescope assignment before the due date

def findNextOpr (txt): I1 II TI >>> findNextOpr(' 3*4 -5') >>> findNextOpr ('89 4 5') I T1 1 if not isinstance (txt,str) or len (txt)>> isNumb False er ("- 156.3) 29.99999999 True 5.9999% ') False I T1 1 if not isinstance (txt, str) or len (txt) 0: return "error: isNumber" YOUCODE STARTS HERE if not isinstance (txt, str) or len (txt)0: return "error: isNumber" YOU CODE STARTS HERE # def getNextNumber (expr, pos): In T1 1 >>> getNextNumber '8 + 5-2',0) >>> getNextNumber '8+ 5-2', 4) >>>getNextNumber ('4.5 + 3.15 (-5.0, None, None) >>>getNextNumber ('4.5 3.15 (None, '/', 19) 1-5',20) 5',10) 1 if not isinstance (expr, str) or not isinstance (pos, int) or len (expr)-0 or pos-len (expr): return None, None, "error: getNextNumber" # YOU CODE STARTS HERE