Type Conversion — input() ka Text ko Number Banana (int, float) -

Intro
Aapne picchle post mein input() use kiya. Bahut badi baat.
Ab ek chhota sa twist: input() hamesha text (string) deta hai.
Isliye aaj hum sikhenge: text ko number kaise banate hain, aur number ko text kaise banate hain.

Concept Explanation

WHY: Type conversion ki zaroorat kyun hoti hai?

Socho aapne user se bola: “Apni age likho”.
User ne likha: 10

Python ne usko number nahi maana. Python ne usko text maana.
Matlab "10".

Ab problem dekho:

"10" + "5" ka matlab hota hai text jodna → "105"
10 + 5 ka matlab hota hai math → 15

Python ko clearly bataana padta hai:
“Ye wali cheez number hai” ya “ye wali cheez text hai”.

Isi ko kehte hain type conversion (ya casting).

HOW: Teen important converters

int()– Jab aapko whole number chahiye (0, 1, 2, 10, 99)

float() -Jab aapko decimal number chahiye (2.5, 10.75)

str()– Jab aapko number ko text banake print karna ho (especially message ke saath jodna ho)

Rule yaad rakho (Blackboard rule)

input() → string
Math karna hai → pehle int() ya float()
Message me number jodna hai → str()

Common mistake (jo beginners karte hain)

Aap int("12.5") karoge to error aayega, kyunki "12.5" decimal hai.
Us case me pehle float("12.5") banana hota hai.

Example

Example 1: Age me 1 add karna
User age dega. Hum next year ki age nikalenge.

# Lesson 9 - Example 1: int() use karke age ko number banana

age_text = input("Enter your age: ")
age = int(age_text)

next_year_age = age + 1
print("Next year your age will be:", next_year_age)

Example 2: Price me total nikalna (float)
Agar chocolate 12.50 ki hai aur aap 2 loge, total nikalenge.

# Lesson 9 - Example 2: float() use karke price ko decimal banana

price_text = input("Enter price of one chocolate (example 12.50): ")
price = float(price_text)

total = price * 2
print("Total price for 2 chocolates:", total)

Try It Yourself

User se “marks” lo (0–100).
Use int() me convert karo.
Print karo: “Your marks are …” (yahan str() ka use karo).

# Lesson 9 - Example 3: str() use karke number ko text banana

marks = 95
print("Your marks are " + str(marks))

Summary

input() hamesha string deta hai.
int() whole number banata hai.
float() decimal number banata hai.
str() number ko text banata hai, taaki message ke saath jod sako.

Next hum numbers ke saath basic math operators (+ - * /) practice karenge.