Pythons int() function does more than just converting a string to integer.The behavior varies based on the argument and an optional base parameter. we can break down behavior as follows:

1. No arguments int() # returns 0
2. Numeric Arguments
   • If the argument if an integer

      int(5) # return 5
   

   • If argument if a float, then it will remove(truncate) the fractional part

      int(2.04) # return 2
   

3. string Arguments
   • int() strips any whitespace, and also can handle an optional sign(+ or -) and then converts the sequence of digits to an integer.

• For example:

int("  -10  ")  # returns -10

• We can also provide an optional base for conversion

int("1010", 2)  # returns 10 (binaray to decimal)

Steps in the conversion process

1. String Handling
   • Strip whitespace.
   • Handling leading sign(+ or -).
2. Validation
   • To check all charters are vailid digits for the given base.
3. Digit conversion
   • Convert each charater to its corresponding numerical value.
4. Accumulation
   • Compute the integer value by iterating through each digit

For example:

def custom_integer_converter(s, base=10):
    # Ensure input is a string
    if not isinstance(s, str):
        raise TypeError("Input must be a string")
    
    s = s.strip().lower()  # Handle whitespace and case insensitivity
    
    if not s:
        raise ValueError("Empty string after stripping whitespace")
    
    # Determine the sign
    sign = 1
    if s[0] == '-':
        sign = -1
        s = s[1:]
    elif s[0] == '+':
        s = s[1:]
    
    if not s:
        raise ValueError("No digits after sign")
    
    # Validate characters and convert to integer
    value = 0
    for c in s:
        # Convert character to numerical value
        if c.isdigit():
            digit = ord(c) - ord('0')
        else:
            digit = ord(c) - ord('a') + 10
        
        # Check if digit is valid for the base
        if not (0 <= digit < base):
            raise ValueError(f"Invalid character '{c}' for base {base}")
        
        value = value * base + digit
    
    return sign * value

enter image description here The image contains the implementation of the code mentioned above, along with tested inputs.