Piye carane format string ing Python?

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Accepted Answer

Python nduweni sawetara cara kanggo mbangun string kanthi nilai dinamis. Pendekatan modern sing direkomendasikake yaiku **f-string** (formatted string literal), sing dikenalake ing Python 3.6.

## f-strings — standar modern default

```python
name = "Ann"
age = 30

msg = f"{name} is {age} years old"   # "Ann is 30 years old"

# any expression works inside the braces
f"{name.upper()} in {age * 12} months"   # "ANN in 360 months"
f"Total: {price * quantity:.2f}"          # format spec: 2 decimals
```

Prefiks `f` ngidini sampeyan nandur expression langsung ing `{}` — ringkas, mudah maca, lan cepet. Iki cara sing disenengi ing Python modern.

## Format specifiers — kontrol output

```python
f"{3.14159:.2f}"     # "3.14"      — 2 decimal places
f"{1000000:,}"        # "1,000,000" — thousands separator
f"{0.85:.1%}"         # "85.0%"     — percentage
f"{42:05d}"           # "00042"     — pad with zeros to width 5
f"{'hi':>10}"         # "        hi" — right-align in width 10
f"{'hi':^10}"         # "    hi    " — center
```

Tandha `:spec` sawise nilai ngontrol presisi, padding, alignment, lan format number — kuat kanggo output sing bersih.

## Shortcut debugging (3.8+)

```python
f"{name=}"            # "name='Ann'" — prints both the expression AND value
```

Tandha `=` iku mangerteni kanggo debugging cepet — nuduhake jeneng variabel lan nilaine.

## Cara lawas (sampeyan isih bakal nemokake)

```python
"{} is {}".format(name, age)     # str.format() — pre-f-string standard
"%s is %d" % (name, age)          # %-formatting — old C-style (avoid in new code)
name + " is " + str(age)          # concatenation — verbose, error-prone
```

`.format()` isih umum ing kode lawas; `%`-formatting yaiku warisan; raw concatenation ora disaranke (verbose lan mbutuhake manual konversi `str()`).

## Kuwi penting

Format string dibutuhake terus-terusan — mbangun pesan, log, output, query.

F-strings yaiku standar modern, mudah maca, lan efisien, lan ngerti format specifiers (presisi, padding, alignment, separator) ngidini sampeyan ngasilake output bersih lan profesional tanpa kode verbose.

Mangerteni gaya `.format()` lan `%` sing lawas membantu nalika maca basis kode sing ana.

Panganggone f-strings kanthi apik yaiku bagean cilik nanging nyebar ing nulis Python sing jelas lan idiomatic.