How to Iterate Over Dictionary in Python: Syntax and Examples

To iterate over a dictionary in Python, use a for loop with dict.keys() to access keys, dict.values() for values, or dict.items() to get both keys and values together. This lets you process each element in the dictionary easily.

Syntax

You can loop through a dictionary in three main ways:

• Keys only: for key in dict.keys():
• Values only: for value in dict.values():
• Keys and values: for key, value in dict.items():

Each method lets you access different parts of the dictionary during iteration.

python

my_dict = {'a': 1, 'b': 2, 'c': 3}

# Iterate keys
for key in my_dict.keys():
    print(key)

# Iterate values
for value in my_dict.values():
    print(value)

# Iterate keys and values
for key, value in my_dict.items():
    print(f"{key}: {value}")

Output

a
b
c
1
2
3
a: 1
b: 2
c: 3

Example

This example shows how to print all keys, all values, and both keys and values from a dictionary.

python

person = {'name': 'Alice', 'age': 30, 'city': 'New York'}

print('Keys:')
for key in person.keys():
    print(key)

print('\nValues:')
for value in person.values():
    print(value)

print('\nKeys and Values:')
for key, value in person.items():
    print(f'{key} -> {value}')

Output

Keys:
name
age
city

Values:
Alice
30
New York

Keys and Values:
name -> Alice
age -> 30
city -> New York

Common Pitfalls

One common mistake is trying to modify a dictionary while iterating over it, which can cause errors or unexpected behavior. Also, using for key in dict: works but is less explicit than dict.keys(). Forgetting to unpack key, value when using dict.items() will cause errors.

python

my_dict = {'x': 10, 'y': 20}

# Wrong: modifying dict during iteration
# for key in my_dict:
#     if key == 'x':
#         del my_dict[key]  # This causes RuntimeError

# Right: iterate over a copy to modify safely
for key in list(my_dict.keys()):
    if key == 'x':
        del my_dict[key]

print(my_dict)

Output

{'y': 20}

Quick Reference

Use these methods to iterate over a dictionary:

Method	Description	Example
dict.keys()	Iterate over keys only	for k in dict.keys():
dict.values()	Iterate over values only	for v in dict.values():
dict.items()	Iterate over keys and values	for k, v in dict.items():

Key Takeaways

Use dict.items() to get both keys and values in a loop.

Avoid changing a dictionary while iterating over it directly.

You can iterate keys with dict.keys() and values with dict.values().

Unpack keys and values properly when using dict.items().

Iterating directly over the dictionary loops over keys by default.