num1 = ""

operator = ""

num2 = ""

def askForInput(textPrompt):

num = input(textPrompt)

try:

# Try to typecast the input to a float

float(num)

except ValueError:

# Catch the exception if it is not a number

print("ERROR: Syn: Invalid Num")

else:

# Else, move on

# Typecasting

return float(num)

while(True):

# Loop for getting operation

while True:

operator = input("What operation do you want to perform? ")

# Is operator == to any of out constants or predefines?

if operator == "help":

operator = ""

elif operator == "pi":

operator = ""

elif operator == "e":

operator = ""

elif operator == "tau":

operator = ""

elif operator == "MR":

operator = ""

elif operator == "M-":

operator = ""

elif operator == "M+":

num2 = "0"

elif operator == "rand":

# Has the user entered in a valid operator?

elif operator == "+" or operator == "-" or operator == "*" or operator == "/" or operator == "^" or operator == "/-" or operator == "!" or operator == "Abs" or operator == "d/r" or operator == "r/d" or operator == "M+" or operator == "M-" or operator == "MR" or operator == "sin" or operator == "cos" or operator == "tan" or operator == "asin" or operator == "acos" or operator == "atan" or operator == "log10" or operator == "log" or operator == "randint":

break

# Loop for 1st number input

while True:

num1 = askForInput("First Number? ")

# Catch asin and acos out of bounds error case

if (operator == "asin" or operator == "acos") and (float(num1) > 1 or float(num1) < -1):

print("ERROR: Math: 'asin' and 'acos' commands only accept inputs in range -1 to +1")

break

# Does the operation require a 2nd input?

if not (operator=="/-" or operator=="!" or operator=="Abs" or operator=="d/r" or operator=="r/d" or operator=="M+" or operator=="sin" or operator=="cos" or operator=="tan" or operator=="asin" or operator=="acos" or operator=="atan" or operator=="log10"):

# Loop for 2nd number input

while True:

num2 = askForInput("Second Number? ")

# Catch x/0 error case

if operator == "/" and num2 == "0":

print("ERROR: Math: Canot divide by 0!")

break

# Calculations

if operator == "+":

output = num1 + num2

print("Your Answer: "+str(output))

if operator == "-":

output = num1 - num2

print("Your Answer: "+str(output))

if operator == "*":

output = num1 * num2

print("Your Answer: "+str(output))

if operator == "/":

output = num1 / num2

print("Your Answer: "+str(output))

if operator == "^":

output = math.pow(num1,num2)

print("Your Answer: "+str(output))

if operator == "/-":

output = math.sqrt(num1)

print("Your Answer: "+str(output))

if operator == "!":

output = math.factorial(num1)

print("Your Answer: "+str(output))

if operator == "Abs":

output = math.fabs(num1)

print("Your Answer: "+str(output))

if operator == "d/r":

output = math.radians(num1)

print("Your Answer: "+str(output))

if operator == "r/d":

output = math.degrees(num1)

print("Your Answer: "+str(output))

if operator == "M+":

memStore = num1

print("Number Stored")

if operator == "sin":

output = math.sin(num1)

print("Your Answer: "+str(output))

if operator == "cos":

output = math.cos(num1)

print("Your Answer: "+str(output))

if operator == "tan":

output = math.tan(num1)

print("Your Answer: "+str(output))

if operator == "asin":

output = math.asin(num1)

print("Your Answer: "+str(output))

if operator == "acos":

output = math.acos(num1)

print("Your Answer: "+str(output))

if operator == "atan":

output = math.atan(num1)

print("Your Answer: "+str(output))

if operator == "log10":

output = math.log10(num1)

print("Your Answer: "+str(output))

if operator == "log":

output = math.log(num2, num1)

print("Your Answer: "+str(output))

if operator == "randint":

output = random.randint(num1, num2)

print("Your Answer: "+str(output))

Assumes the user does not know anything about programming in python.

* Supports the functions `+,-,*,/`

Tutorial:

* Can convert `Degrees to Radians, Radians to Degrees`

Tutorial:

In python, printing to the command line can be done using the `print()` statement. The only required argument is a string to be printed. For example, in Python 3, `print("Hello World")` will print `Hello World` to the command line.

In python, user input on the command line can be taken by using the command `input()`. Putting in a string (optional) as a paramter will give the user a prompt after which they can input text. This statement returns a string with the text the user typed, so it needs to be assigneed to a variable. This can be done in python like so, `myvar = input("Feed me data! ")`. Python is not a language with strongly wyped variables, which means that you do not have to define a type when you create a variable. The interpreter will automatically assign the variable a type the first time it is instantiated with data.

Querying input from the user for a calculation can be done like so,

```num1 = input("Hello, What is your First Number?\n")

This code will print a prompt asking for a first number to the screen, ask for input, print a prompt asking for an operation to the screen, ask for input, etc. The `\n` at the end of the strings is an escape character that tells python to add a newline to the end of the prompt. I did this so that the user would start typing on the line below the prompt. (personal asthetic taste)

In order for us to do math on the numbers that the user typed, we need to convert them to numerical values, as you cannot do math on strings, for obvious reasons. (After all, what is "abc" / "def" anyways?) The method for doing so is called Typecasting. and in Python, you can convert to float (decimal numbers less than 7 digits) by using the float() statement. This can be done for our purposes like so,

```floatnum1 = float(num1)

Now that we have the numbers converted to float types, we are ready to do the math. For simplicity's sake in this lesson, we will use `if()` statements to tell what the user wants to do. In this program, we will support four operations, +,-,* and /, so we will need to have 4 if statements. One if statement for this program will look like,

```if operation == "+":

This checks to see if the user wanted to add the two numbers, and if they did, it adds them together.

Repeat the following for the following three operations.

Using the `print()` statement, we can print the result out to the screen. In Python, strings can be concatenated by "adding" them together, as if they were numbers. The code for this step looks like this: `print("Your Answer: "+str(output))`. This code prints the text "Your answer: " concatenated with the output, after it has been typecasted to a string. (You can't concatenate it while it is still formatted as a float)

Amazing! You have made a simple command line based calculator! If you understood all of the code in this lesson, and you have gotten the code to compile, please continue onto the advanced tutorial.