Concatenation means joining strings together. In Python, you use the + operator to concatenate strings:

print("Hello" + " " + "world")

This outputs: Hello world

You can also print strings and numbers together by separating them with commas in the print() function:

print("I am a student and I am aged", 15)
print("2 + 2 =", 2 + 2)

Note the difference:

• The + operator concatenates strings (joins them with no space)
• Commas in print() separate multiple values (adds a space between them)

Important Rule

You cannot concatenate a string and a number directly with +. This will cause an error:

print("I am " + 14 + " years old")  # Error!

You must convert the number to a string first using str():

print("I am " + str(14) + " years old")

Or use commas instead:

print("I am", 14, "years old")

Fix the Code

Can you spot and fix the errors in each of these lines?

print("hello " + "world")

print("I am Jerry, and I am", 14, "years old")

print("I'm Jerry and I'm " + str(14) + " years old")