You\u2019ve just started writing a Python program and then it hits you: a TypeError. This one\u2019s 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.
<\/p>\n\n\n\n
In this guide, we\u2019re going to talk about what this Python error means and how you can solve it. We\u2019ll walk through an example program with this error so that you can see how it works. Without further ado, let\u2019s get started!<\/p>\n\n\n\n
In Python, values can only be concatenated<\/a> 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:<\/p>\n\n\n\n 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\u2019ve got to convert the integer to a string first before you concatenate it to a string.<\/p>\n\n\n\n This error is raised when you try to concatenate a string<\/a> and an integer. Let\u2019s take a look at a program which suffers from this problem: This program prints out how many copies of the book The Great Gatsby<\/em> are in stock at a bookstore. First, we declare a dictionary<\/a> 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. Let\u2019s try to run our code:<\/p>\n\n\n\n As we expected, a TypeError has been raised.<\/p>\n\n\n\n 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<\/a>, which converts an integer to a string:<\/p>\n\n\n\n Let\u2019s try to run our code again:<\/p>\n\n\n\n Our code has found how many copies of The Great Gatsby<\/em> 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. “X” refers to how many copies are in stock.<\/p>\n\n\n\ntypeerror: can only concatenate str (not "int") to str<\/pre><\/div>\n\n\n\n
An Example Situation<\/h2>\n\n\n\n
<\/p>\n\n\n\n
<\/p>\n\n\n\ngatsby = {\n\t"title": "The Great Gatsby",\n\t"author": "F. Scott Fitzgerald",\n\t"price": 4.99,\n\t"quantity_in_stock": 4\n}\n\nprint("There are " + gatsby["quantity_in_stock"] + " copies of The Great Gatsby in stock.")<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
<\/p>\n\n\n\nTraceback (most recent call last):\nFile "main.py", line 8, in <module>\n\tprint("There are " + gatsby["quantity_in_stock"] + " copies of The Great Gatsby in stock.")\nTypeError: can only concatenate str (not "int") to str<\/pre><\/div>\n\n\n\nThe Solution<\/h2>\n\n\n\n
<\/p>\n\n\n\nprint("There are " + str(gatsby["quantity_in_stock"]) + " copies of The Great Gatsby in stock.")<\/pre><\/div>\n\n\n\nThere are 4 copies of The Great Gatsby in stock.<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
<\/p>\n\n\n\n