Hướng dẫn {:d} in python

Question

These are all informative answers, but none are quite getting at the core of what the difference is between %s and %d.

Nội dung chính Show

%d in Python String Formatting
%s in Python String Formatting
Comparison Between %s and %d Operators in Python
Related Article - Python String
What is %d and %f in Python?
What does %s means in Python?
Why %F is used in Python?
What is the difference between %S and %D?

Nội dung chính

%d in Python String Formatting
%s in Python String Formatting
Comparison Between %s and %d Operators in Python
Related Article - Python String
What is %d and %f in Python?
What does %s means in Python?
Why %F is used in Python?
What is the difference between %S and %D?

%s tells the formatter to call the str() function on the argument and since we are coercing to a string by definition, %s is essentially just performing str(arg).

%d on the other hand, is calling int() on the argument before calling str(), like str(int(arg)), This will cause int coercion as well as str coercion.

For example, I can convert a hex value to decimal,

>>> '%d' % 0x15
'21'

or truncate a float.

>>> '%d' % 34.5
'34'

But the operation will raise an exception if the argument isn't a number.

>>> '%d' % 'thirteen'
Traceback (most recent call last):
  File "", line 1, in 
TypeError: %d format: a number is required, not str

So if the intent is just to call str(arg), then %s is sufficient, but if you need extra formatting (like formatting float decimal places) or other coercion, then the other format symbols are needed.

With the f-string notation, when you leave the formatter out, the default is str.

>>> a = 1
>>> f'{a}'
'1'
>>> f'{a:d}'
'1'
>>> a = '1'
>>> f'{a:d}'
Traceback (most recent call last):
  File "", line 1, in 
ValueError: Unknown format code 'd' for object of type 'str'

The same is true with string.format; the default is str.

>>> a = 1
>>> '{}'.format(a)
'1'
>>> '{!s}'.format(a)
'1'
>>> '{:d}'.format(a)
'1'

Python uses C-style string formatting to create new, formatted strings. The "%" operator is used to format a set of variables enclosed in a "tuple" (a fixed size list), together with a format string, which contains normal text together with "argument specifiers", special symbols like "%s" and "%d".

Let's say you have a variable called "name" with your user name in it, and you would then like to print(out a greeting to that user.)

# This prints out "Hello, John!"
name = "John"
print("Hello, %s!" % name)

To use two or more argument specifiers, use a tuple (parentheses):

# This prints out "John is 23 years old."
name = "John"
age = 23
print("%s is %d years old." % (name, age))

Any object which is not a string can be formatted using the %s operator as well. The string which returns from the "repr" method of that object is formatted as the string. For example:

# This prints out: A list: [1, 2, 3]
mylist = [1,2,3]
print("A list: %s" % mylist)

Here are some basic argument specifiers you should know:

%s - String (or any object with a string representation, like numbers)

%d - Integers

%f - Floating point numbers

%.f - Floating point numbers with a fixed amount of digits to the right of the dot.

%x/%X - Integers in hex representation (lowercase/uppercase)

Exercise

You will need to write a format string which prints out the data using the following syntax: Hello John Doe. Your current balance is $53.44.

data = ("John", "Doe", 53.44) format_string = "Hello" print(format_string % data) data = ("John", "Doe", 53.44) format_string = "Hello %s %s. Your current balance is $%s." print(format_string % data) #test_output_contains("Hello John Doe. Your current balance is $53.44.", no_output_msg= "Make sure you add the `%s` in the correct spaces to the `format_string` to meeet the exercise goals!") test_object('format_string') success_msg('Great work!')

HowTo
Python How-To's
Difference Between %s and %d in Python String Formatting

Created: May-28, 2021 | Updated: August-10, 2021

The tutorial explains the difference between %s and %d in Python string formatting. We will first describe the use of %s and %d separately and then compare the usage of both operators. The tutorial provides detailed examples with codes to clearly state the usage and difference between %s and %d in Python.

%d in Python String Formatting

The %d operator is used as a formatting string in Python. It is a placeholder for an integer. The value associated with %d is provided in a tuple using % or modulo operator. It is necessary to maintain the order of the values to be printed. However, if the Python version is 3, then the print statement will be given in parenthesis; otherwise, the print statement is not given in parenthesis.

An example code is given below to illustrate further how to use %d in Python.

age = 10
print ("John Doe is %d years old" %age)

Output:

John Doe is 10 years old

However, in the case of floating-point numbers, the %d operator automatically converts them to decimal values. An example code is given below.

area = 24.6
print("The area of this plot is %d sq meter." %area)

Output:

The area of this plot is 24 sq meter.

%s in Python String Formatting

In Python, % is used with different data types for different purposes. %s is used as a placeholder for the string values. However, it is specifically used for the purpose of string concatenation. A string formatter can take any value and place it inside the string with automatic type conversion. It can be used to append multiple values to a string. An example code is given below to demystify the use of %s in Python.

name = "john doe"
print("The name of the applicant is %s." %name)

Output:

The name of the applicant is john doe.

Comparison Between %s and %d Operators in Python

A comparison between %s and %d operators in Python is given below.

`%s`	`%d`
It is used as a placeholder for string values	`%d` is used as a placeholder for integer values
It can accept any other data type as well	If a string is specified for %d operator in Python, it will give an error
The string conversion is done using the `str()` method. The conversion is done before formatting	The conversion in %d is done, before formatting, using the `int()` method.

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Remove Whitespace From a String in Python

What is %d and %f in Python?

Answer. In Python, string formatters are essentially placeholders that let us pass in different values into some formatted string. The %d formatter is used to input decimal values, or whole numbers. If you provide a float value, it will convert it to a whole number, by truncating the values after the decimal point.

What does %s means in Python?

%s specifically is used to perform concatenation of strings together. It allows us to format a value inside a string. It is used to incorporate another string within a string. It automatically provides type conversion from value to string.

Why %F is used in Python?

Python string formatting It uses the % operator and classic string format specifies such as %s and %d . Since Python 3.0, the format function was introduced to provide advance formatting options. Python f-strings are available since Python 3.6. The string has the f prefix and uses {} to evaluate variables.

What is the difference between %S and %D?

The technical difference between %s and %d is simply that %d calls int() on the argument before calling str(). Of course, you can't call int() on a string, or on anything else but a number.

programming python {:,} python D in Python D Python Format trong Python 0.2f in Python

Hướng dẫn {:d} in python

Exercise

%d in Python String Formatting

%s in Python String Formatting

Comparison Between %s and %d Operators in Python

Related Article - Python String

What is %d and %f in Python?

What does %s means in Python?

Why %F is used in Python?

What is the difference between %S and %D?

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