如何将不同数量的 arguments 从元组传递到 python 中的字符串格式？

Question

I am facing a difficulty in passing varying number of arguments from tuple to string format. Sometimes my tuple consists of only one value, but sometimes up to 10 values. If I want to print all of the values in print statement how do I do that? I have tried:

tup = ('val1', 'val2', 'val3')
print('List consists of: {}'.format(*tup))

but it prints out only the first value. Unfortunately, each time I have varying number of arguments to print.

Answer 1

Remove the * so you are not unpacking the tuple:

tup = ('val1', 'val2', 'val3')
print('List consists of: {}'.format(tup))

Output:

List consists of: ('val1', 'val2', 'val3')

Answer 2

You don't need .format() or .join() in this case. Just pass *tup as agument to the print function:

>>> tup = ('h', 'e', 'l', 'l', 'o', 'world')
>>> print(*tup)
h e l l o world

It works for number's too;

tup = (1, 2 ,3)

print('List consists of:', *tup)

[OUTPUT]: List consists of: 1 2 3

And you can add separators if you want;

print('List consists of:', *tup, sep=', ')

[OUTPUT]: List consists of: 1, 2, 3

Answer 3

The special syntax *args ( *mystrings in our case) in function definitions in python is used to pass a variable number of arguments to a function. It is used to pass a non-keyworded, variable-length argument list .

The nice thing here that they are passed as a tuple by python which make this a Classic and strait forward approach. see this approach in the code snippet bellow:

def foo(*mystrings): ## which ofen used as *args
    for string in mystrings:
    print(string)    ## Or do what ever you want.

Now call it:

tup = ('val1', 'val2', 'val3')
foo(tup)

If you want just to construct a string from the tuple you can use join() method to do the job:

strt=' '.join(tup)

str.join(iterable)

Return a string which is the concatenation of the strings in iterable. A TypeError will be raised if there are any non-string values in iterable, including bytes objects. The separator between elements is the string providing this method.