Code Template - String formatting

1. f-strings

name = "Alice"
age = 25
value = 3.14159
 
# Insert variables 
f"Hello {name}, you are {age} years old"
# Format the variables 
f"Pi is approximately {value:.2f}"
f"Percentage: {0.85:.1%}"
f"Scientific: {1234:.2e}"

2. Common Format Specifiers

Format	Description	Example	Output
:.2f	2 decimal places	f"{3.14159:.2f}"	3.14
:.0f	No decimals	f"{3.14159:.0f}"	3
:d	Integer	f"{42:d}"	42
:.1%	Percentage	f"{0.85:.1%}"	85.0%
:.2e	Scientific notation	f"{1234:.2e}"	1.23e+03
:>10	Right align, width 10	f"{'hi':>10}"	hi
:<10	Left align, width 10	f"{'hi':<10}"	hi
:^10	Center align, width 10	f"{'hi':^10}"	hi

3. Padding and Alignment

# Zero padding for numbers
f"{42:05d}"        # "00042"
f"{3.14:08.2f}"    # "00003.14"
 
# String alignment
f"{'text':>10}"    # "      text"
f"{'text':<10}"    # "text      "
f"{'text':^10}"    # "   text   "

4. Quick Reference for Numbers

x = 1234.5678
f"{x:.2f}"     # 1234.57 (2 decimals)
f"{x:,.2f}"    # 1,234.57 (with commas)
f"{x:8.2f}"    # " 1234.57" (width 8, right aligned)
f"{x:08.2f}"   # "01234.57" (zero padded)

5. Date/Time Formatting

from datetime import datetime
now = datetime.now()
f"{now:%Y-%m-%d}"      # 2025-07-16
f"{now:%H:%M:%S}"      # 14:30:45
f"{now:%B %d, %Y}"     # July 16, 2025

7. Exam-Ready Quick Tips

• Always use f-strings for new code (fastest, most readable)
• Remember the colon before format specifiers: {value:.2f}
• Common patterns: .2f (decimals), ,.0f (integers with commas), .1% (percentages)
• Width and alignment: > (right), < (left), ^ (center)
• Zero padding: 05d for integers, 08.2f for floats