Cool Mojo Calculator

calculator.mojo

# Cool Mojo Calculator
from types.input.input import input

def is_float(given_string: String) -> Bool:
    # Given a string, go through each character and check if it is a digit or a dot.
    for i in range(len(given_string)):
        # If the character is a dot, check if it is the last character in the string.
        if given_string[i] == "." and i == len(given_string) - 1:
            return False
        # Normal case, check if the character is a digit or a dot.
        if isdigit(ord(given_string[i])) or given_string[i] == ".":
            continue
    return True

fn string_to_float32(owned origin_string: String) raises -> Float32:
    # Start by checking if the given string is even a float.
    if not is_float(origin_string):
        raise Error("The given string is not a float.")

    # Find the index of the dot.
    var dot_index: Int = 0
    var found_dot: Bool = False
    for i in range(len(origin_string)):
        if origin_string[i] == ".":
            dot_index = i
            found_dot = True
            break
    if not found_dot:
        dot_index = len(origin_string)
        origin_string += ".0"

    # Get the first half of the string and convert it to an integer.
    var first_half_string: String = origin_string[0:dot_index]
    if first_half_string == "":
        first_half_string = "0"
    let first_half: Int = atol(first_half_string)

    # Get the second half of the string and convert it to an integer.
    let second_half: Float32 = Float32(atol(origin_string[dot_index + 1:]))

    # Get the length of the second half and divide it by 10 to the power of the length to get the float value.
    let second_half_float: Float32 = second_half / (10 ** len(origin_string[dot_index + 1:]))

    # Add the two halves together and return the result.
    let result: Float32 = first_half + second_half_float
    return result

fn main():
    # Define some variables.
    var first_num_word: String = "first number"
    var second_num_word: String = "second number"
    let first_num: Float32
    let second_num: Float32

    # Start the program.
    print("Welcome to my simple Mojo calculator!")

    # Get the operation to perform.
    let operation: String = input("Please enter the operation you would like to perform (+, -, *, /): ")
    if operation == "/":
        first_num_word = "dividend"
        second_num_word = "divisor"
        
    # Get the two numbers.
    while True:
        try:
            first_num = string_to_float32(input("Please enter the " + first_num_word + ": "))
            second_num = string_to_float32(input("Please enter the " + second_num_word + ": "))
            break
        except e:
            print("Invalid input, please try again.")

    # Perform the operation.
    var result: Float32 = 0.0
    if operation == "+":
        result = first_num + second_num
    elif operation == "-":
        result = first_num - second_num
    elif operation == "*":
        result = first_num * second_num
    elif operation == "/":
        result = first_num / second_num

    # Print the result.
    print("The result is: " + String(result))