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Python, can I concatenate a string and an int?
I started learning Python. I created this simple code which involves concatenating a string and an integer. I just found out that Python doesn't like that. Here is the code I'm typing. Python gave me an error message because of line 4.
character_name = "John"
character_age = 35
print("There was a man named " + character_name + ".")
print("He was " + character_age + " years old")
character_name = "Mike"
print("There was someone else named " + character_name + ".")
print("But he didn't like being 35")
How do I concatenate a string an in int
character_name = "John"
character_age = 35
print("There was a man named " + character_name + ".")
print("He was " + character_age + " years old")
character_name = "Mike"
print("There was someone else named " + character_name + ".")
print("But he didn't like being 35")
How do I concatenate a string an in int
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You cannot concatenate a string and an integer.
Howver you can convert the integer to a string to concatenate or you can use string formatting.
There's two different kinds of string formatting.
The 'old style formatting', that's more similiar to the printf formatting style of the C language
and the new formatting style which is more powerful, but a little more to type for simple cases.
Old style with the '%' operator
New style formatting with the .format() method
Documentation for new style formatting:
https://docs.python.org/3/library/string.html?highlight=string#string.ascii_uppercase
and examples at
https://docs.python.org/3/library/string.html?highlight=string#formatexamples
Documentation for old style formatting:
https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting
Howver you can convert the integer to a string to concatenate or you can use string formatting.
There's two different kinds of string formatting.
The 'old style formatting', that's more similiar to the printf formatting style of the C language
and the new formatting style which is more powerful, but a little more to type for simple cases.
Old style with the '%' operator
New style formatting with the .format() method
Documentation for new style formatting:
https://docs.python.org/3/library/string.html?highlight=string#string.ascii_uppercase
and examples at
https://docs.python.org/3/library/string.html?highlight=string#formatexamples
Documentation for old style formatting:
https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting
character_name = "John"
character_age = 35
print("There was a man named " + character_name + ".")
print("There was a man named %s." % character_name)
print("There was a man named {}.".format(character_name))
print("He was " + str(character_age) + " years old")
print("He was %d years old" % character_age)
print("He was {} years old".format(character_age))
print("The man %s was %d years old" % (character_name, character_age))
print("The man {} was {} years old".format(character_name, character_age))
character_name = "Mike"
print("There was someone else named " + character_name + ".")
print("But he didn't like being 35")
To add to Gelonida's answer, you can use also the format_map() method of the string (since Python 3.2), where the curly braces can contain the name of the key to the dictionary.
This is nice if you already have the dictionary filled for other purposes. (The above is a bit clumsy.)
However, since Python 3.6, there is new and nice feature called formatted string literals. You simply add the f prefix before the literal, and then you just put the name of the variable inside the curly braces:
Actually, you can write the expression inside:
(The feature is known also in other programming languages.)
>>> character_name = 'John'
>>> character_age = 35
>>> 'The man {name} was {age} years old'.format_map({'name': character_name, 'age': character_age})
'The man John was 35 years old'
This is nice if you already have the dictionary filled for other purposes. (The above is a bit clumsy.)
However, since Python 3.6, there is new and nice feature called formatted string literals. You simply add the f prefix before the literal, and then you just put the name of the variable inside the curly braces:
>>> character_name = 'John'
>>> character_age = 35
>>> f'The man {character_name} was {character_age} years old'
'The man John was 35 years old'
Actually, you can write the expression inside:
>>> f'The man {character_name.upper()} was {character_age + 10} years old'
'The man JOHN was 45 years old'
(The feature is known also in other programming languages.)
@pepr: True.
the new formatted string literal is the third way of formatting which I forgot to mention
even the old style % operator supports map formatting.
So if you have a dict instead of separate viarables, then it's also possible to do.
the new formatted string literal is the third way of formatting which I forgot to mention
even the old style % operator supports map formatting.
So if you have a dict instead of separate viarables, then it's also possible to do.
info = { "name": "John", "age": 35}
# old style
print("The name is %(name)s and the age is %(age)d" % info)
# new style
print("The name is {name} and the age is {age}".format_map(info))
Thank you both.
Geez, I didn't know that something so seemingly simple as concatenation could be so involved.
Geez, I didn't know that something so seemingly simple as concatenation could be so involved.
Also it can be written in short like this...
>>> character_name = 'john'
>>> character_age = 35
>>> 'The man {} was {} years old'.format(character_name,character_age)
'The man john was 35 years old'
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