How to Concatenate Strings in Python

What you’ll build or solve

You’ll combine strings in Python using the most common approaches: +, join(), and f-strings.

When this approach works best

This approach works best when you:

• Build user-facing messages, like "Hello, Mina!" or status updates.
• Combine data into a label or key, like "order-" + order_id.
• Generate output from lists, like turning ["a", "b", "c"] into "a,b,c".

Avoid this approach when:

• You are building huge text in a tight loop. Prefer collecting pieces in a list and using join().

Prerequisites

• Python installed
• You know what a string and a list are

Step-by-step instructions

1) Concatenate with + for simple cases

Use + when you have a few strings to combine.

first="Ada"
last="Lovelace"

full_name=first+" "+last
print(full_name)

If you want to add punctuation or spacing, include it as a string:

message="Hello, "+first+"!"
print(message)

2) Use f-strings for readable formatting

f-strings let you embed values inside a string. This is often the clearest choice for messages.

name="Mina"
score=92

message=f"{name} scored{score} points."
print(message)

What to look for: f-strings convert values to text for you, so you don’t need str(score).

3) Use join() to concatenate many pieces

If you have a list of strings, join() is usually the best option.

words= ["learn","python","today"]
sentence=" ".join(words)
print(sentence)

You can pick any separator:

tags= ["python","data","web"]
csv=",".join(tags)
print(csv)

What to look for: All items must be strings. Convert first if needed.

4) Convert non-strings before concatenating

If you use + with a non-string, Python raises a TypeError. Convert values with str() or switch to an f-string.

count=3

label="items: "+str(count)
print(label)

Using an f-string is often simpler:

count=3
label=f"items:{count}"
print(label)

5) Build text in a loop using a list, then join()

When you concatenate repeatedly in a loop, collect parts first, then join once.

names= ["Ada","Mina","Sam"]
parts= []

fornameinnames:
parts.append(f"-{name}")

result="\n".join(parts)
print(result)

This stays fast and keeps your code easy to read.

Examples you can copy

Example 1: Build a greeting

first_name="Sam"
greeting="Hi "+first_name+"!"
print(greeting)

Example 2: Create a filename from pieces

user_id=42
date="2026-02-12"

filename=f"user-{user_id}-{date}.txt"
print(filename)

Example 3: Join a list into a comma-separated string

cities= ["Podgorica","Budva","Kotor"]
line=", ".join(cities)
print(line)

Example 4: Join non-strings by converting first

This example uses a generator expression to convert numbers to strings.

numbers= [1,2,3,4]
text=" - ".join(str(n)forninnumbers)
print(text)

Common mistakes and how to fix them

Mistake 1: Concatenating a string with an int

What you might do:

count=5
message="Total: "+count
print(message)

Why it breaks: + only works between strings, not between a string and an integer.

Correct approach: Convert or use an f-string.

count=5
message="Total: "+str(count)
print(message)

count=5
message=f"Total:{count}"
print(message)

Mistake 2: Using join() on a list that contains non-strings

What you might do:

items= ["A",2,"C"]
text=",".join(items)
print(text)

Why it breaks: join() requires every item to be a string.

Correct approach: Convert items first.

items= ["A",2,"C"]
text=",".join(str(x)forxinitems)
print(text)

Troubleshooting

If you see TypeError: can only concatenate str (not "int") to str, do this: convert with str(value) or use an f-string.

If you see TypeError: sequence item 1: expected str instance, do this: convert items before join(), like str(x) for x in items.

If your output has missing spaces, do this: add separators explicitly, like " ", ", ", or "\n".

If concatenation feels slow in a loop, do this: append to a list and call join() once at the end.

If you see extra separators at the end, do this: avoid manual += "," patterns, and use join().

Quick recap

• Use + to concatenate a few strings.
• Use f-strings for readable messages with variables.
• Use join() to concatenate many strings from a list.
• Convert non-strings with str() or use f-strings.
• For loops, collect parts in a list, then call join() once.