typeerror can only concatenate str not int to str что значит
Python typeerror: can only concatenate str (not “int”) to str Solution
You’ve just started writing a Python program and then it hits you: a TypeError. This one’s new to you: “typeerror: can only concatenate str (not “int”) to str”. What does it mean? Why is it being raised in your code? These are all good questions.
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In this guide, we’re going to talk about what this Python error means and how you can solve it. We’ll walk through an example program with this error so that you can see how it works. Without further ado, let’s get started!
The Problem: typeerror: can only concatenate str (not “int”) to str
In Python, values can only be concatenated if they are the same type. You cannot concatenate a string and an integer, or a string and a list. If you do, a TypeError is raised:
There are a few programming languages, like JavaScript, which allow you to concatenate strings and integers together. In Python, you cannot do this. If you want to concatenate a string and an integer, you’ve got to convert the integer to a string first before you concatenate it to a string.
An Example Situation
This error is raised when you try to concatenate a string and an integer.
Let’s take a look at a program which suffers from this problem:
This program prints out how many copies of the book The Great Gatsby are in stock at a bookstore. First, we declare a dictionary called “gatsby”. This dictionary contains four pieces of information about the book: its title, the author, its price, and how many copies are in stock.
Next, we print out a message informing the user how many copies are in stock at the bookstore.
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Let’s try to run our code:
As we expected, a TypeError has been raised.
The Solution
The value of gatsby[“quantity_in_stock”] is an integer. A TypeError has been raised because we have tried to concatenate that value, an integer, to a string.
We can solve this problem by converting the value of gatsby[“quantity_in_stock”] to a string before we concatenate it to our other strings. We can do this using the str() method, which converts an integer to a string:
Let’s try to run our code again:
Our code has found how many copies of The Great Gatsby are in stock. Then, it has printed out how many copies are in stock to the console. This value is printed in the following format:
There are X copies of The Great Gatsby in stock.
How to resolve “TypeError: can only concatenate str (not “int”) to str” in Python?
Exercise: Run the script and reproduce the error! Study this article to learn how to fix it!
This article will answer every question that beginners may ask about this topic.
About The TypeError
If we want our variable to be of the int type, we must write it down in this way:
The result of this script will be as follows:
As we can see, our variable is ‘ int ‘ type.
So, how do we do it in Python?
After repeating the basics, you may still not notice the mistake you have made, so I will give you a possible reason for this error.
When in Python we want to do some mathematical operations, we have to use numbers (as you know for sure), so our numbers cannot be in quotation marks, namely if we want to add numbers, e.g., 10 and 5 to each other, then in Python it will look like this:
A TypeError would be caused by this script:
Fix 1: Convert to the Correct Data Type Manually
Check your script and locate a potential error, then correct this line of code.
Second, you remove the quotes and our program should work.
However, this method is ineffective for more complex programs, because you do it all manually.
Fix 2: String Conversion
Find out in which line of code TypeError appeared and before the variables insert the data type you are interested in, when you want to add numbers to yourself, let’s do so:
Then you are sure that these are the numbers and will definitely be added to each other, and when you want to add two words to each other, then you do so:
using this method, two subtitles will surely be joined together.
However, this method is not optimal when you have a lot of data that you want to combine with each other, because you have to spend a lot of time. So, lets move on to method number 3!
Fix 3: Conversion Function
Creation of a function that automatically converts a variable type into another specified type, on condition that you know that the variables do not store letters (if you want to change their type to int ). You can create a basic function that only works on 2 variables:
But what if you want to do a function that will work for example on 5 variables? In that case, you need to write the function:
Next, you can overwrite our variables so you can use them without a list:
or not overwrite them and use the list for e.g. mathematical operations:
Fix 4: Use an IDE like PyCharm
By using an IDE that checks for errors, such as PyCharm. If you don’t know where the bug is and you’re not using the IDE, it’s worth downloading one to make it easier to find the bug in the code.
Alternative cause of TypeError:
If you just wanted to write something like «I have 3 cats» and you used pluses instead of commas:
Simply change the pluses to commas:
Summary
We repeated the basics of the int and str types in Python and discovered that Python will not change the variable type for us, we have to use the int() or str() function ourselves, depending on what we want to achieve. This article also provides 4 methods that can be used to prevent TypeError and one other reason for this error.
I hope this blog article has helped you understand the possible cause of the problem in your script.
Sources:
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TypeError: Can only concatenate str (not «int») to str (simple Python programme)
I am using Python 3.7.0 in Windows 10
11 Answers 11
The input() command in line 2 of your code would turn any input provided by the user into a STRING. Therefore, when you try to add that STRING to a number (float or integer; in your case you have an integer i.e. factor=2) it won’t (and shouldn’t!) work.
Therefore, for the + operation to continue, both the quantities to the left and right of that + sign must be of the same type (strings, or numbers)
TypeError: Can only concatenate str (not “int”) to str
This Error states that it can only concatenate string to string. In your program you have tried to concatenate a sting and integer
Input command would only fetch string from the user, and the age the user enters should be taken as string. Examples: ’45’, ’25’, 36 etc..
Instead you can try converting the user input to int and then concatenate.
Python is strongly typed, so it does not do type coercion unless you tell it to.
You get that error if you try to add a number to a string, because based on the first operand it figures you want to concatenate strings.
If you try to add a string to a number, you get “unsupported operand types” instead, but it’s the same problem.
Convert age to int to do your maths:
In python, you cannot concatenate two completely different data types.
Well, in other programming languages like C, the integer would be converted into char (or character) and would undergo operation 2.
Example: int(‘7’) would yield 7
So, you either need to take the input as integer or else convert the string to integer while computing finalAge :
TypeError: can only concatenate str (not «int») to str
TypeError: can only concatenate str (not «int») to str
In this article we will learn about the error TypeError: can only concatenate str (not «int») to str.
This error generates when we try to concatenate an int value to a string. Unlike many other languages, in python, we can not directly typecast an int value to the string. If we try to do so an error TypeError: can only concatenate str (not «int») to str generates.
Let us understand it more with the help of an example.
Example:
Output:
In line 9 of the code, we are trying to concatenate an int value i.e ‘age’ to string values. Which is not allowed in Python and thus raising the TypeError.
Solution:
The solution for the above TypeError is to convert the int value ‘age’ to a string value and then try to concatenate.
We can explicitly convert ‘int’ value to a ‘string’ value using a built-in function str( ).
str( ) converts the arguments passed into a string explicitly.
Do ‘str(age)’ instead of ‘age’ in line 9 of the code. This will convert the int value ‘age’ to string and we can perform concatenation without an issue.
Как работает конкатенация строк в Python 3? Примеры.
Конкатенация строк — самая распространенная операция в программировании на Python. Есть несколько варинатов как сложить две строки.
Конкатенация строк в Python
Варианты обьединения строк:
Конкатенация строк с помощью оператора ‘+’
Это самый простой способ. Давайте рассмотрим на примере:
Результат: «Pythonist.ru нужен Питонисту»
Давайте рассмотрим другой пример, где мы получаем 2 строки от пользователя и потом конкатенируем их.
Результат: Конкатенированная строка = pythonist.ru сайт для программистов
Очень удобный способ использование оператора «+». Единственный момент, который надо учитывать это то, что обе вводные должны быть строками.
Мы можем использовать str() function для представленя объекта в виде строки.
Давайте посмотрим как конкатенировать строку и число или другой объект.
Основная проблема оператора «+» в том, что используя его мы не можем добавить разделитель между строками. Например если мы хотим сконкатенировать строки “Hello” и “World” и поставить между ними пробел, то нам надо писать так «Hello» + » » + «World»
Конкатенация строк используя функцию join().
Мы можем использовать функцию join() для конкатенации строк и одновременного добавления разделителя между ними. Это полезная функция, когда мы имеем последовательность строк, например List или tuple строк.
Если вам не нужен разделитель, то можно использовать join() с пустой строкой.
Результат:
Concatenated String using join() = HelloWorld
Concatenated String using join() and spaces = Hello World
Конкатенация строк используя оператор %
Мы можем использовать оператор % как для форматирования строк, так и для конкатенации. Он полезен когда нам нужно сложить две строки и вдобавок отфарматировать.
String Concatenation using % Operator = Hello World
String Concatenation using % Operator with Formatting = Hello World from JournalDev — 2018
Конкатенация строк с помощью функции format()
Можно использовать функцию строк format() для конкатенации и форматирования.
String Concatenation using format() = Hello-World
String Concatenation using format() = Hello World
Функция format() очень мощная и использовать ее только для сложения строк не самый лучший и быстрый вариант.
Конкатенация с использованием f-строк
Если вы используете Python3.6+ то вы можете использовать f-строки для конкатенации. Это новый способ форматирования строк. Он был представлен в PEP 498 – Literal String Interpolation.
String Concatenation using f-string = Hello World
Pankaj age is 34 and d=Data[10]
Python f-строки более чистый и легкий способ по сравнению с format()
Заключение
Форматирование строк в Python может быть сделано разными способами. Используйте один из них, в зависимости, что вам нужно сделать со строками. Если надо сконкатенировать и добавить разделитель, тогда используйте Join(). Если надо еще и отформатировать, тогда format() или f-строки. Учитывайте что f-строки можно использовать с версии Python3.6 или выше.