`print()`, comments, code structure — Hinglish notes

1.2.2 · Coding › Introduction to Programming (Python)

1. `print()` — insaan se baat karna

Behaviour ko first principles se derive karna

Hum guess nahi karte ki print() kya karta hai — hum sabse chhote cases try karke reasoning karte hain.

print("Hello")        # 1 argument: a string
print(42)             # 1 argument: a number
print("Sum:", 2 + 3)  # 2 arguments
print()               # 0 arguments

print("Sum:", 2 + 3) Sum: 5 kyun dikhata hai?

Step 1: Python pehle har argument ko evaluate karta hai. "Sum:" "Sum:" hi rehta hai; 2 + 3 5 ban jaata hai. Yeh step kyun? Python hamesha value compute karta hai pehle, phir use function ko deta hai.
Step 2: print multiple arguments ko by default ek space se jodta hai aur unhe likhta hai.
Step 3: print end mein automatically ek newline (\n) add karta hai. Kyun? Taaki har print apni alag line par aaye — yahi sabse common zaroorat hoti hai.

Worked example

sep aur end ko control karna

print("a", "b", "c", sep="-")     # a-b-c
print("loading", end="...")       # loading...  (no newline!)
print("done")                     # ...done  -> prints right after

loading...done ek hi line par kyun? Kyunki pehla print "..." ke saath khatam hua na ki newline ke saath, isliye agla print usi line par continue karta hai.

2. Comments — insaanon ke liye notes

# This whole line is ignored.
print("Hi")          # everything after # on THIS line is ignored
radius = 5           # store the radius in cm
area = 3.14159 * radius ** 2   # πr²

Worked example "Docstring" style multi-line note

Python mein koi true multi-line comment nahi hai, lekin ek triple-quoted string jo standalone line ki tarah use ho woh ek jaisi kaam karti hai:

"""
This program prints a greeting.
Author: you
"""
print("Welcome")

Yeh kyun kaam karta hai: yeh ek string hai jo kisi cheez ko assign nahi ki gayi, toh yeh harmlessly discard ho jaati hai — insaan ise padhte hain, program ka effect ignore hota hai.

3. Code structure — Python ek file kaise padhta hai

Figure — `print()`, comments, code structure

Worked example Ek chhote program ko computer ki tarah padhna

# 1. compute, 2. show
name = "Asha"          # line A: store text
greeting = "Hi, " + name   # line B: build a string
print(greeting)        # line C: display it -> Hi, Asha

Trace, "har step kyun" ke saath:

Line A pehle chalta hai → name mein "Asha" store hota hai. Kyun pehle? top-to-bottom.
Line B name use karta hai (jo already exist karna chahiye) → greeting = "Hi, Asha". Iske liye line A kyun zaroori hai? tum koi value use nahi kar sakte pehle usse create kiye bina.
Line C print karta hai. Kyun aakhri? yeh aakhri line hai.

Recall Forecast-then-Verify — aage padhne se

pehle output predict karo

print("X", end="|")
print("Y", "Z", sep="", end="!")
print()
print("next")

Predict karo, phir check karo: Line1 → X| · Line2 → YZ! (turant baad) · Line3 → sirf newline · Line4 → naye line par next. Final screen:

X|YZ!
next

Active recall — flashcards

print Python mein kis tarah ka construct hai?

Ek built-in function.

print() ke parentheses ke andar jo values hoti hain unhe kya kehte hain?

Arguments.

print by default apne arguments ke baad kya add karta hai?

Ek newline (end="\n").

print by default multiple arguments ke beech kya rakhta hai?

Ek single space (sep=" ").

print() ki return value kya hoti hai?

None (iska asli kaam text dikhane ka side effect hai).

print ko naye line par jaane se kaise rokein?

end="" pass karo (ya koi bhi string jo tum chahte ho).

Single-line comment kaunse symbol se shuru hota hai?

#.

Kya Python comments execute karta hai?

Nahi — unhe bilkul ignore kiya jaata hai.

print(Hello) (bina quotes) kyun fail hota hai lekin print("Hello") kaam karta hai?

Bina quotes ke Hello ko ek variable name maana jaata hai → NameError; quotes use literal string banate hain.

Statements by default kis order mein run hote hain?

Top to bottom, ek line at a time.

print("A","B",sep="-") kya output deta hai?

A-B.

Ek achha comment ___ explain karta hai, obvious ___ nahi.

why ; what.

Recall Feynman: ek 12-saal ke bachche ko explain karo (hidden)

Socho computer ek super-fast lekin andha helper hai. Woh apne dimag mein maths karta hai aur cheezein yaad rakhta hai, lekin tum kuch nahi dekh sakte. print() helper se yeh kehne jaisa hai: "woh bol do zor se taaki main sun sakun!" — sirf isi tarah tum pata laga sakte ho ki use kya pata hai. Ek comment (#) un sticky notes ki tarah hai jo tum apni instructions ke paas likhte ho: helper unhe padhke aage badh jaata hai, woh sirf tumhare liye hain taaki tum yaad rakh sako ki har step kyun likha. Aur helper hamesha tumhari instructions page ke upar se neeche, order mein follow karta hai, kabhi aage nahi jump karta.

Connections

Variables and Assignment — print woh dikhata hai jo variables hold karte hain.
Strings and Quotes — text ko " " ki zaroorat kyun hai.
f-strings and String Formatting — print ke liye text banane ke sundar tarike.
Functions, Arguments, and Return Values — print ek function hai; sep/end keyword arguments hain.
Indentation and Code Blocks — structure rule jo if/for use karta hai.
None and Truthiness — kyun print None return karta hai.

1. print() — insaan se baat karna

Behaviour ko first principles se derive karna

2. Comments — insaanon ke liye notes

3. Code structure — Python ek file kaise padhta hai

Active recall — flashcards

Connections

Concept Map

1. `print()` — insaan se baat karna