#60 strings and numbers

[Florin Oprea]

Hi,

Variable Assignment - Automatically change the type of a variable is a good thing. It must remain so.

a=1    #Integer
a="x"  #Now 'a' is a string

But those lines should not work:

print "5" / "5"        # 1.0
print 5 * "5"          # 25.0
print "2e3" - 2e3      # 0.0
print "2"^2            # 4.0

I don´t think that a string shoud be so versatile.
All those lines should generate errors.

Also, numbers should be stored as integers as much as possible. print 5 / 5 should print 1, not 1.0. Stored or (maybe) just printed so.

Respectfully,
Florin Oprea

[Jim Reneau]

Actualy, this is the expected behaviour. If a string contains a number and "math" (not + concatenate) is done to it, BASIC-256 tries to convert it. It allows for old "INPUT X" statement to imput a string with a number in it and still work like a number.

The "/" operator is division and will ALWAYS return a float, the "\" operator is integer division and will always return an integer. This behaviour is like Python and I found it easier for students to understand.

[Florin Oprea]

INPUT command is the only place where the user assign a string or a number to a variable.
Would not it be better to try to figure out what the user entered only there?

INPUT a

If the user enters "text" then a will be a string variable.
If the user enters "15" then we have an integer.
If user enters "15.1" then a will be a float variable.

If the progam wants to ensure that the input is expected type then it can use safe alternatives: input float, input integer or input string. Or convert input to desired type with string(), int() or float().
"Never trust user input", right?

So, i think changing input command is the key:
input - guess input type
input float - convert text into float - if no float, then return 0.0
input integer - convert text into integer - if no integer, then return 0
input string - return text

Just that.

Think about the following questions:
1) How many errors can meet a user if you change just the way it works INPUT command? (Remember that it is perfectly compatible with older versions: the INPUT a$ / INPUT a)
2) How many errors can occur if the variables are automatically converted at every step?

Please consider this. Not necessarily hold in my opinion, but I really believe in its simplicity.

Respectfully,
FLorin Oprea

[Jim Reneau]

The INPUT statement (for some time - I just checked the code) behaves as you suggested.

input ">>",a
print a + " " + typeof(a)

• enter the integer 99 and 99 1 is printed
• enter the float 99.99 and 99.99 2 is printed
• enter a string hola and hola 3 is printed

Your input matters and I really appreciate it.
Jim