We will learn about Nested for loop in Python programming language
Already, we learnt about for loop in python. In python programming language, a for loop inside another for loop is called as nested for loop.
Nested for loop has two parts of the loop
Outer for loop executes only once when its test expression is true. Then, the flow of control moves to inner loop iteration and inner loop executes until its test expression is false.
When the test expression of the inner loop is false, the flow of control skips the execution of the inner loop and come out to execute the outer loop again.
Syntax
The syntax of nested for loop in python
The flow diagram in nested for loop in Python
When we execute the above program, it will produce the following result
Example
program 1
for i in range(3):
print("x")
for i in range(4):
print("y")
When we execute the above program, it will produce the following result
x x x y y y y
Program 2
for i in range(3):
print("letter X")
for i in range(4):
print("letter Y")
When we execute the above program, it will produce the following result
letter X letter Y letter Y letter Y letter Y letter X letter Y letter Y letter Y letter Y letter X letter Y letter Y letter Y letter Y
Program 3
#nested for loop in python
for i in range(0,3):
for j in range(0,4):
print(i,j)
When we execute the above program, it will produce the following result
(0, 0) (0, 1) (0, 2) (0, 3) (1, 0) (1, 1) (1, 2) (1, 3) (2, 0) (2, 1) (2, 2) (2, 3)
Program 4
Display Floyd’s triangle
#nested for loop in python example
num=int(input("Enter te number of rows :"))
print(" ")
for i in range(1,num):
for j in range(1):
print("*"*(i)), #string multiplication
print("")
When we execute the above program, it will produce the following result
Enter the number of rows: 7
* ** *** **** ***** ******
program 5
display multiplication table 1
for i in range(1,11)://#outer for loop
print(" ")
for j in range(1,11)://#outer for loop
print(i*j),
print("\t"),
When we execute the above program, it will produce the following result
1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 5 10 15 20 25 30 35 40 45 50 6 12 18 24 30 36 42 48 54 60 7 14 21 28 35 42 49 56 63 70 8 16 24 32 40 48 56 64 72 80 9 18 27 36 45 54 63 72 81 90 10 20 30 40 50 60 70 80 90 100
Program 6
display multiplication table 2
for i in range(1,5,1):
print("\n"),
for j in range(1,6,1):
print i,'*',j,'=',i*j,
print("\n"),
When we execute the above program, it will produce the following result
1 * 1 = 1 1 * 2 = 2 1 * 3 = 3 1 * 4 = 4 1 * 5 = 5 2 * 1 = 2 2 * 2 = 4 2 * 3 = 6 2 * 4 = 8 2 * 5 = 10 3 * 1 = 3 3 * 2 = 6 3 * 3 = 9 3 * 4 = 12 3 * 5 = 15 4 * 1 = 4 4 * 2 = 8 4 * 3 = 12 4 * 4 = 16 4 * 5 = 20
Program 7
find the prime number using nested for loop
for var1 in range(2,20):
bol=True
for var2 in range(2,var1-1):
if(var1%var2==0):
print(var1, "is not prime number")
bol=False
break
if bol:
print(var1, "is a prime number")
When we execute the above program, it will produce the following result
(2, 'is a prime number') (3, 'is a prime number') (4, 'is not prime number') (5, 'is a prime number') (6, 'is not prime number') (7, 'is a prime number') (8, 'is not prime number') (9, 'is not prime number') (10, 'is not prime number') (11, 'is a prime number') (12, 'is not prime number') (13, 'is a prime number') (14, 'is not prime number') (15, 'is not prime number') (16, 'is not prime number') (17, 'is a prime number') (18, 'is not prime number') (19, 'is a prime number')
We can use nested for loop in multiple lists in Python
Program 1
names=['John','Smith','Dan','Khan']#name is string
//#name list in Python
ages=[34,54,23,43] //#age list in Python, age is int
for name in names: //#outer for loop
for age in ages: //#inner for loop
print name," has "+str(age)
When we execute the above program, it will produce the following result
John has 34
John has 54
John has 23
John has 43
Smith has 34
Smith has 54
Smith has 23
Smith has 43
Dan has 34
Dan has 54
Dan has 23
Dan has 43
Khan has 34
Khan has 54
Khan has 23
Khan has 43
Program 2
names=['Jhon','Smith','Dan']#name is string
#name list in Python
numbers=[1,4,6] #numbere list in Python
cars=['Benz','Toyota','BMW'] #car list in python
for name in names:
for number in numbers:
for car in cars:
print name+" has "+str(number)+"car"+car
When we execute the above program, it will produce the following result
Jhon has 1carBenz Jhon has 1carToyota Jhon has 1carBMW Jhon has 4carBenz Jhon has 4carToyota Jhon has 4carBMW Jhon has 6carBenz Jhon has 6carToyota Jhon has 6carBMW Smith has 1carBenz Smith has 1carToyota Smith has 1carBMW Smith has 4carBenz Smith has 4carToyota Smith has 4carBMW Smith has 6carBenz Smith has 6carToyota Smith has 6carBMW Dan has 1carBenz Dan has 1carToyota Dan has 1carBMW Dan has 4carBenz Dan has 4carToyota Dan has 4carBMW Dan has 6carBenz Dan has 6carToyota Dan has 6carBMW
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