Fill in program

The randint(a,b) function from Python's random module returns a "random" integer in the range from a to b, including both end point. Fill in the blanks in the function below that creates and returns a random string of 0's and 1s of length n.

from random import randint:
def randString01(n):
    _________________
    _________________
    for count in range(n):
        __________________
    return________________

(Ed: The : at the end of the import statement doesn't belong; it's as presented in the original question, however.)

...so far i found out how to make n into a string of the length of n(so a string of n n's) I want to know where would the randint apply? So far i have

from random import randint
def randString01(num): 
    x = str() 
    count = num 
    while count >0: 
        if randint(0,1) == 0: 
            append.x(0)   
        else: 
            append.x(1) 
        count -= 1
    x=str(x) 
    re开发者_Go百科turn x

but it doesnt work. What should I fix?

Since this is homework, I won't give you the answer, but here are some leading questions:

• How would you use randint(a,b) to give you either 0 or 1?
• How do you convert an integer to a string?
• How can you build up a string with a for loop?

If you can answer those, you've solved the problem.

Inside the for-loop.

Since it's clearly classwork, here's some pseudo-code to start with:

define randString01(num):
    set str to ""
    count = num
    while count is greater than zero:
        if randint(0,1) is zero:
            append "0" to str
        else:
            append "1" to str
        subtract one from count
    return str

Your string of n occurences of the character n will not help here by the way. It will either give you a zero-sized "0" string or a one-sized "1" string. In other words, all ones.

Okay, what you have in your comment seems okay (at least in structure):

from random import randint
def randString01(num):
    x = str()                       ## <-- ???
    count = num
    while count > 0:
        if randint(0,1) == 0:
            append.x(0)             ## <-- ???
        else:
            append.x(1)             ## <-- ???
        count -= 1
    x = str(x)                      ## <-- ???
    return x

but I'm just a little uncertain about your str() and append() lines. Since you've done the bulk of the work, here are my minor changes to get this going under Python:

from random import randint
def randString01(num):
    x = ""
    count = num
    while count > 0:
        if randint(0,1) == 0:
            x = x + "0"
        else:
            x = x + "1"
        count -= 1
    return x

print randString01(7)               ## And add these to call the function.
print randString01(7)
print randString01(9)
print randString01(9)

This outputs:

1011000
1010011
110001000
110101001

if you don't have to use the exact syntax above, this can be accomplished with 1 line of code.

concepts:

string.join takes an iterable you can create an iterable of random string by inlining the for loop in to a list comprehension

the resulting code is as follows.

''.join([str(random.randint(0,1)) for i in range(n)])