Delete object in array within another array while checking for valid index-CodePudding

The task is to delete an object from an array within another array (a touple if i'm correct). To bugproof i would need to check whether the index is actually valid. This means ranges from 0 to 4 (so input should be greater 0 smaller 4) and obviously not be a string or float of any kind.

I have tried to do that with my def function. i obviously want loopx to only be false if indeed both of the above mentioned criteria are met. otherwise i would want to jump to except. I felt like if that is what I've done but now been stuck for over an hour.

#Write a Python program to delete an existing item from the array

#function used to check for valid input
def valuecheck(checker):
  loopx = True
  while loopx:
    try:
      if checker == int(checker) and (checker>0 and checker<4):
      #first it checks if the input is actually an integer
      #checker = int(checker) 
      #checks if the input index number is within range of the array
        loopx = False 
      else:
        checker = input("Value isn't a valid input, try again: ")
      return(checker)
      #if input isn't an integer the below prompt is printed
    except:
      checker = input("Value isn't a valid input, try again: ")

#the example array is defined and printed
myarray = ['i', [1, 3, 5, 7, 9]]
print(myarray[1])

#input defined and checked by the loop
deletion = input("Please input the index of the element you want to remove (0 through 4). Indexes for the elements start at 0, increasing left to right: ")
deletion = valuecheck(deletion)

#pop is then used to remove the value with index "deletion" from the array
myarray[1].pop(deletion)
#finally the new array is printed
print ("This is the new array:",myarray[1])

CodePudding user response：

Here is a version of the valuecheck() function that should do what you want:

def valuecheck(checker):
    while True:
        try:
            checker = int(checker)
            if checker > 0 and checker < 4:
                return checker
            checker = input("Value must be between 1 and 3, try again: ")
        except:
            checker = input("Value must be an integer, try again: ")

The main difference to your code is that the value in checker is converted to an integer before it is tested to check if it's in the range 1-3. That operation will throw an exception if checker doesn't contain the string representation of a valid integer.

Rather than using the loop variable loopx, the function simply returns when it finds a valid value.

CodePudding user response：

Try this code (it contains only little differences respect yours):

#Write a Python program to delete an existing item from the array

#function used to check for valid input
def valuecheck(checker):
    loopx = True
    while loopx:
        try:
            if (int(checker)>=0 and int(checker)<=4):
                loopx = False
            else:
                checker = input("Value isn't a valid input, try again: ")
        except Exception as ex:
            checker = input("Value isn't a valid input, try again: ")
    return checker

#the example array is defined and printed
myarray = ['i', [1, 3, 5, 7, 9]]
print(myarray[1])

#input defined and checked by the loop
deletion = input("Please input the index of the element you want to remove (0 through 4). Indexes for the elements start at 0, increasing left to right: ")
deletion = valuecheck(deletion)

#pop is then used to remove the value with index "deletion" from the array
myarray[1].pop(int(deletion))
#finally the new array is printed
print ("This is the new array:",myarray[1])

In my opinion the condition is:

if (int(checker)>=0 and int(checker)<=4):

because your array contains 5 elements.

CodePudding user response：

def valuecheck():
    prompt = "Please input the index of the element you want to remove (0 through 4). Indexes for the elements start at 0, increasing left to right: "
    while True:
        try:
            checker = int(input(prompt))
            if 0 <= checker <= 4:
                return checker
            prompt = "Value isn't in range [0,4], try again: "
        except ValueError:
            prompt = "Value isn't a valid integer, try again: "

#the example array is defined and printed
myarray = ['i', [1, 3, 5, 7, 9]]
print(myarray[1])

#input defined and checked by the loop
deletion = valuecheck()

#pop is then used to remove the value with index "deletion" from the array
myarray[1].pop(deletion)
#finally the new array is printed
print ("This is the new array:",myarray[1])

The function will only return with a value when it can convert the input string to an integer and it's between 0 and 4 (inclusive). In other cases it changes the prompt's text and the loop continues.

I also specified the type of exception in the except clause as your program won't exit if you press Ctrl C (KeyboardInterrupt) if you don't specify.