print() parameters and formatting in Python - Time & Space Complexity

Time Complexity: print() parameters and formatting

O(n)

Understanding Time Complexity

We want to understand how the time it takes to run print() changes when we use different parameters and formatting.

How does the number of items or formatting affect the time print() needs?

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

for i in range(n):
    print(f"Number: {i}", end=' ', flush=False)
print()

This code prints numbers from 0 to n-1 on the same line with a space, then moves to a new line.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The print() function inside the loop.
• How many times: It runs once for each number from 0 to n-1, so n times.

How Execution Grows With Input

As n grows, the number of print calls grows the same way.

Input Size (n)	Approx. Operations
10	10 print calls
100	100 print calls
1000	1000 print calls

Pattern observation: The time grows directly with the number of items printed.

Final Time Complexity

Time Complexity: O(n)

This means the time to print grows in a straight line as you print more items.

Common Mistake

[X] Wrong: "Changing print formatting or parameters does not affect time complexity at all."

[OK] Correct: While formatting itself is fast, more complex formatting or flushing output can add small extra time per print, but the main time still grows with how many times print runs.

Interview Connect

Understanding how print and formatting scale helps you think about how programs handle output efficiently, a useful skill for writing clear and fast code.

Self-Check

"What if we added flush=True inside the print call? How would the time complexity change?"

Practice

1. What does the sep parameter do in the print() function?

easy

A. It changes the separator between multiple items printed.

B. It changes the ending character of the printed line.

C. It formats numbers inside the print statement.

D. It pauses the program before printing.

Solution

1. Step 1: Understand the role of sep

   The sep parameter defines what string is placed between multiple items printed.

2. Step 2: Compare with other parameters

   end changes line ending, formatting is done by f-strings, and pausing is unrelated.

3. Final Answer:

   It changes the separator between multiple items printed. -> Option A

4. Quick Check:

   sep = separator [OK]

Hint: Remember: sep controls spacing between items [OK]

Common Mistakes:

• Confusing sep with end parameter
• Thinking sep formats numbers
• Assuming sep pauses output

2. Which of the following is the correct syntax to print two words separated by a dash using print()?

easy

A. print('hello' - 'world')

B. print('hello' + 'world', sep='-')

C. print('hello', 'world', end='-')

D. print('hello', 'world', sep='-')

Solution

1. Step 1: Identify correct use of sep

   Using sep='-' between multiple arguments prints them separated by a dash.

2. Step 2: Check syntax correctness

   print('hello', 'world', sep='-') uses correct syntax. print('hello' + 'world', sep='-') concatenates strings before printing, ignoring sep. print('hello', 'world', end='-') uses end, which changes line ending, not separator. print('hello' - 'world') is invalid syntax.

3. Final Answer:

   print('hello', 'world', sep='-') -> Option D

4. Quick Check:

   sep='-' joins words with dash [OK]

Hint: Use sep between items, not inside strings [OK]

Common Mistakes:

• Using + operator with sep parameter
• Confusing sep with end
• Trying to subtract strings

3. What is the output of this code?

print('A', 'B', 'C', sep='*', end='!')
print('D')

medium

A. A*B*C!D

B. A B C ! D

C. A*B*C
D

D. A B C!D

Solution

1. Step 1: Analyze first print()

   It prints 'A', 'B', 'C' separated by '*', ending with '!'. So output is 'A*B*C!'

2. Step 2: Analyze second print()

   It prints 'D' on the same line because first print ended with '!' (no newline).

3. Final Answer:

   A*B*C!D -> Option A

4. Quick Check:

   sep='*', end='!' joins and ends line [OK]

Hint: Remember end='' keeps output on same line [OK]

Common Mistakes:

• Assuming default space separator
• Thinking end adds newline
• Ignoring end parameter effect

4. The following code prints 'Score:-10'. What is the fix to print 'Score: 10'?

print('Score:', score, sep='-')

Assuming score = 10.

medium

A. Convert score to string before printing.

B. Change sep to end parameter.

C. Remove sep parameter or use it correctly between multiple items.

D. Add parentheses around score.

Solution

1. Step 1: Understand sep usage

   The sep='-' parameter places '-' between 'Score:' and score, resulting in 'Score:-10'.

2. Step 2: Identify the fix

   To print 'Score: 10' with default space separator, remove the sep parameter.

3. Final Answer:

   Remove sep parameter or use it correctly between multiple items. -> Option C

4. Quick Check:

   remove sep -> default space [OK]

Hint: Use sep only when printing multiple items [OK]

Common Mistakes:

• Confusing sep with end parameter
• Trying to convert variables unnecessarily
• Using sep with single string

5. How can you print the number 7.12345 rounded to 2 decimal places using print() and f-strings?

hard

A. print(f'{7.12345:2f}')

B. print(f'{7.12345:.2f}')

C. print(f'{7.12345:.2}')

D. print(f'{7.12345:.f2}')

Solution

1. Step 1: Understand f-string formatting

   To round a float to 2 decimals, use :.2f inside the braces.

2. Step 2: Check each option

   print(f'{7.12345:.2f}') uses correct syntax {value:.2f}. print(f'{7.12345:2f}') misses the dot before 2. print(f'{7.12345:.2}') uses wrong format specifier. print(f'{7.12345:.f2}') has incorrect order.

3. Final Answer:

   print(f'{7.12345:.2f}') -> Option B

4. Quick Check:

   Use .2f to round floats in f-strings [OK]

Hint: Use .2f inside f-string to round floats [OK]

Common Mistakes:

• Omitting the dot before precision
• Using wrong format specifiers
• Mixing order of letters and numbers