for sikli va range()

7-bob 29 kod bloki 2453 so'z

Nega sikl kerak?

1 dan 5 gacha sonlarni chiqarish kerak bo'lsin. Siklsiz:

print(1)
print(2)
print(3)
print(4)
print(5)

1
2
3
4
5

1 dan 1000 gacha bo'lsa-chi? 1000 qator yozmaymiz. Sikl (loop) bir xil ishni kerakli marta takrorlaydi:

for i in range(1, 6):
    print(i)

1
2
3
4
5

Uni shunday o'qing: "1 dan 6 gacha (6 kirmaydi) har bir i uchun — i ni chiqar". Har bir aylanishda i navbatdagi qiymatni oladi: 1, 2, 3, 4, 5.

Tuzilishi if ga o'xshaydi: oxirida :, takrorlanadigan qatorlar 4 probel ichkarida.

range(): sonlar ketma-ketligi

range() ning uch shakli bor:

for i in range(5):
    print(i, end=" ")
print()
for i in range(2, 8):
    print(i, end=" ")
print()
for i in range(0, 21, 5):
    print(i, end=" ")
print()
for i in range(10, 0, -2):
    print(i, end=" ")

0 1 2 3 4 
2 3 4 5 6 7 
0 5 10 15 20 
10 8 6 4 2 

Qoida kesish (slicing) bilan bir xil: oxiri kirmaydi. range(5) — aynan 5 ta son.

print(..., end=" ") sonlarni bitta qatorga yozadi, bo'sh print() esa yangi qatorga o'tkazadi.

n = 5
for i in range(1, n):
    print(i, end=" ")
print("<- 5 yo'q!")
for i in range(1, n + 1):
    print(i, end=" ")

1 2 3 4 <- 5 yo'q!
1 2 3 4 5 

Agar takrorlash sonining o'zi kerak bo'lmasa, o'zgaruvchi o'rniga _ yoziladi:

for _ in range(3):
    print("Salom!")

Salom!
Salom!
Salom!

Satr bo'ylab yurish

for satrning har bir belgisini navbat bilan oladi:

for harf in "Python":
    print(harf)

P
y
t
h
o
n

Satrdagi unli harflarni sanaymiz:

gap = "Men dasturlashni o'rganyapman"
unlilar = 0
for harf in gap.lower():
    if harf in "aeiou":
        unlilar += 1
print("Unli harflar soni:", unlilar)

Unli harflar soni: 9

Bu yerda if sikl ichida, shuning uchun 8 probel ichkarida.

Yig'indi: accumulator andozasi

Sikl bilan eng ko'p qilinadigan ish — yig'ish. Andoza uch qadamdan iborat:

1. Sikldan oldin natija o'zgaruvchisini boshlang'ich qiymat bilan oching: jami = 0.
2. Sikl ichida uni yangilang: jami += i.
3. Sikldan keyin natijani chiqaring.

jami = 0
for i in range(1, 101):
    jami += i
print("1 dan 100 gacha yig'indi:", jami)

1 dan 100 gacha yig'indi: 5050

Ko'paytma uchun boshlang'ich qiymat 1 bo'ladi (0 ga ko'paytirsak, hammasi 0 bo'lib qoladi):

n = 5
faktorial = 1
for i in range(1, n + 1):
    faktorial *= i
print(f"{n}! = {faktorial}")

5! = 120

jami = 0
for i in range(1, 5):
    jami += i
    print("Yig'indi:", jami)

Yig'indi: 1
Yig'indi: 3
Yig'indi: 6
Yig'indi: 10

Foydalanuvchidan N ta son olish

Sikl ichida input() ham bo'lishi mumkin:

n = int(input("Nechta son? "))
jami = 0
eng_katta = None
for i in range(n):
    x = int(input(f"{i + 1}-son: "))
    jami += x
    if eng_katta is None or x > eng_katta:
        eng_katta = x
print("Yig'indi:", jami)
print("O'rtacha:", jami / n)
print("Eng kattasi:", eng_katta)

Nechta son? 4
1-son: 12
2-son: 7
3-son: 20
4-son: 5
Yig'indi: 44
O'rtacha: 11.0
Eng kattasi: 20

None — "hali qiymat yo'q" degan maxsus qiymat. Birinchi son kelganda u darhol eng_katta ga yoziladi. is None bilan tekshiriladi.

Ichma-ich sikl

Sikl ichida yana sikl bo'lishi mumkin. Ichki sikl tashqi siklning har bir aylanishida boshidan oxirigacha yuradi:

for i in range(1, 6):
    for j in range(1, 6):
        print(f"{i * j:4}", end="")
    print()

   1   2   3   4   5
   2   4   6   8  10
   3   6   9  12  15
   4   8  12  16  20
   5  10  15  20  25

{i * j:4} — har bir sonni 4 belgi joyda o'ngga tekislab chiqaradi (5-bob), shuning uchun ustunlar tekis.

Yulduzchalar bilan uchburchak:

for i in range(1, 6):
    print("*" * i)

*
**
***
****
*****

Bu yerda ichki sikl kerak bo'lmadi: "*" * i satrni takrorlaydi (2-bob).

break va continue

• break — siklni darhol to'xtatadi.
• continue — joriy aylanishning qolganini tashlab, keyingisiga o'tadi.

for i in range(1, 11):
    if i % 3 == 0:
        continue
    if i > 8:
        break
    print(i, end=" ")

1 2 4 5 7 8 

3 ga bo'linadiganlar (3, 6) continue bilan o'tkazib yuborildi, 9 da break siklni to'xtatdi. Ularni 8-bobda while bilan ko'p ishlatamiz.

Xulosa

• for i in range(a, b, qadam): — a dan b gacha, b kirmaydi.
• 1 dan n gacha — range(1, n + 1).
• for harf in satr: — har bir belgi bo'ylab.
• Yig'indi: jami = 0 → jami += x; ko'paytma: p = 1 → p *= x; sanoq: soni += 1.
• Natijani chiqaradigan print sikldan keyin, chekinishsiz.
• break — to'xtatish, continue — keyingisiga o'tish.

Mashqlar

Bir nechta son chiqarish kerak bo'lsa, ularni probel bilan bitta qatorga yoki har birini alohida qatorga chiqarishingiz mumkin — tekshiruvchi uchun farqi yo'q.

k = int(input())
n = int(input())
for _ in range(n):
    print(k, end=" ")

a = int(input())
b = int(input())
for i in range(a, b + 1):
    print(i, end=" ")
print(b - a + 1)

a = int(input())
b = int(input())
for i in range(b - 1, a, -1):
    print(i, end=" ")
print(b - a - 1)

narx = float(input())
for kg in range(1, 11):
    print(narx * kg, end=" ")

a = int(input())
b = int(input())
s = 0
for i in range(a, b + 1):
    s += i
print(s)

a = int(input())
b = int(input())
p = 1
for i in range(a, b + 1):
    p *= i
print(p)

a = int(input())
b = int(input())
s = 0
for i in range(a, b + 1):
    s += i * i
print(s)

n = int(input())
s = 0
for i in range(1, n + 1):
    s += 1 / i
print(s)

n = int(input())
s = 0
for i in range(n, 2 * n + 1):
    s += i * i
print(s)

a = float(input())
n = int(input())
p = 1
for _ in range(n):
    p *= a
print(p)

n = int(input())
f = 1
for i in range(1, n + 1):
    f *= i
print(f)

n = int(input())
f = 1
s = 0
for i in range(1, n + 1):
    f *= i
    s += f
print(s)

s = input()
k = 0
for h in s.lower():
    if h in "aeiou":
        k += 1
print(k)

n = int(input())
for i in range(1, 11):
    print(f"{n} x {i} = {n * i}")

n = int(input())
s = 0
for i in range(1, n + 1):
    if i % 3 == 0 or i % 5 == 0:
        s += i
print(s)