Merging strings with "%" in Python

Question

Can someone tell me what's wrong with this bit of code and what to change?

number = 1
text = "hello"

while number <= 10:
    print("%d, %s" % number, text)
    number = number + 1

Error:

Traceback (most recent call last): File "program.py", line 5, in print("%d, %s" % number + text) TypeError: not enough arguments for format string

It works when I do it this way:

number = 1
text = "hello"

while number <= 10:
    print("%d" % number)
    number = number + 1

I think i read somewhere that using the "%" sign to merge strings is the old way to do it, I'd like the code to still use it if it's possible.

The error message and code are not for the same execution. Make sure to not misrepresent either. — user2864740, Sep 22 '19 at 15:38
@user2864740 Oh sorry about that, was going to ask something else and I didn't replace the text correctly, not gonna happen again. — MentalCombination, Sep 22 '19 at 15:45
`format` and `f`-strings are preferred for generating text now. — jpmc26, Sep 22 '19 at 22:53

score 2 · Answer 1 · answered Sep 22 '19 at 15:33

2

Doing it this way requires parentheses around number, text, as it requires a tuple. So just replace the line print("%d, %s" % number, text) with print("%d, %s" % (number, text)) and you should be good.

answered Sep 22 '19 at 15:33

Nobozarb

334
1
12

score 1 · Answer 2 · answered Sep 22 '19 at 14:53

1

use this code

number = 1
text = "hello"

while number <= 10:
    print("%d, %s" % (number, text))
    number = number + 1

answered Sep 22 '19 at 14:53

ali sarkhosh

143
1
10

kuro · Answer 3 · 2019-09-22T16:04:41.360

In print("%d, %s" % number, text) statement, you need to provide a tuple of parameters to the string formatting (in your case "%d, %s"). So, the correct way to do this is -

print("%d, %s" % (number, text))

or

print number, text  # applicable for python 2.7
# print (number, text) # Python 3. Python 2.7 prints a tuple

The second one is applicable as you are not printing anything other that the variables. For the first one you need a tuple for where you are providing more than one arguments during string formatting. So, if want to print say only number, you can do just print ("%d" %number) or print "%d" %number. The tuple in this case is not mandatory, but you can always do print ("%d" %(number,)) if you really want to type some more characters.

But the first one is old way of doing things. For newer and more cooler version, use format() like below -

print("{}, {} blah blah blah".format(number, text))

or,

print "{}, {} blah blah blah".format(number, text)

For more info, check out - https://docs.python.org/2/library/string.html#format-string-syntax

Also follow the answer given by @lenik for other problems in your code.

score 0 · Answer 4 · answered Sep 22 '19 at 15:45

Your code is absolutely against all the rules of the python code. Should have been written like this:

text = 'hello'
for number in range(10) :
    print( number, text )

No unneeded initializations for number
No while loop, which often leads to errors
No formatting where not necessary

Merging strings with "%" in Python

4 Answers4