L3.9: Formatted Printing

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Learning outcomes

• use f-strings for clear output
• apply width/alignment/precision specifiers
• print report-style tables cleanly
• solve formatted-output MCQ traps

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Why formatted printing matters

• better readability
• predictable alignment in tables
• easier output checking in exams

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f-string basics

name = "Aarav"
score = 87
print(f"{name} scored {score}")

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Width and alignment

• right align: :>8
• left align: :<8
• center align: :^8

x = 42
print(f"|{x:>6}|")
print(f"|{x:<6}|")
print(f"|{x:^6}|")

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Numeric precision

pi = 3.1415926
print(f"{pi:.2f}")   # 3.14
print(f"{pi:.4f}")   # 3.1416

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Zero padding

n = 500
print(f"{n:06}")  # 000500

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Percentage display

ratio = 0.8734
print(f"{ratio:.1%}")  # 87.3%

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Mini table example

items = [("Pen", 10, 12.5), ("Book", 3, 45.0), ("Bag", 1, 950.0)]
print(f"{'Item':<10}{'Qty':>5}{'Price':>10}")
for name, qty, price in items:
    print(f"{name:<10}{qty:>5}{price:>10.2f}")

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Exam traps

• width controls minimum field size, not max cutoff
• :06 works for numeric zero-padding
• mixing numeric format on string value causes error

s = "500"
# print(f"{s:06d}")  # ValueError/format error for string with integer code

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Practice

1. Print number 73 as 000073.
2. Print float 12.34567 to 3 decimal places.
3. Print name centered in width 12.
4. Create a 3-column student marks table.

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Quick answers

1. print(f"{73:06}")
2. print(f"{12.34567:.3f}")
3. print(f"{'Riya':^12}")