1) To add space between strings
txt = "TodayIsFriday"
#Today is Friday
first = True
for letter in txt:
if letter>='A' and letter<='Z':
if first==True:
first = False
else:
print(' ',end='')
print(letter,end='')
Output:
Today Is Friday
2)To remove space between strings
txt = " Today Is Friday"
#Today is Friday
for letter in txt:
if letter==' ':
pass
else:
print(letter,end='')
Output:
TodayIsFriday
3) ltrim- To remove spaces in left side of the strings.
#ltrim
txt = " Today Is Friday"
#Today is Friday
alphabet = False
for letter in txt:
if letter==' ' and alphabet == False:
pass
else:
alphabet = True
print(letter,end='')
4) rtrim- To remove spaces in right side of the strings.
txt = "Today Is Friday "
#Today is Friday
alphabet = False
i = len(txt)-1
while i>=0:
letter = txt[i]
if letter==' ' and alphabet == False:
pass
else:
alphabet = True
end = i
j = 0
while j<=end:
print(txt[j],end='')
j+=1
break
i-=1
Output:
Today Is Friday
5) Removing Unwanted spaces from given String
txt = "Today Is Friday"
#Today is Friday
i = 0
while i<len(txt):
if txt[i] != ' ':
print(txt[i],end='')
else:
if txt[i-1]!=' ':
print(txt[i],end='')
i+=1
Output:
Today Is Friday
Recursion:
Function calling itself.
Looping-->Iterative approach.
Recursion-->Recursive approach.
Example:1
def display(no):
print(no, end=' ')
no+=1
if no<=5:
display(no)
display(1)
Output:
1 2 3 4 5
Recursive function for calling factorial:
5!=5x4x3x2x1 (or) 5x4!
4!=4x3x2x1 (or) 4x3!
3!=3x2x1 (or) 3x2!
2!=2x1 (or) 2x1!
1!=1
Example:2
def find_fact(no):
if no==1:
return 1
return no * find_fact(no-1)
result = find_fact(5)
print(result)
Output:
120
Explanation:
1) find_fact(5)
Returns 5 * find_fact(4) #no-1 = 5-1 -->4
2) find_fact(4)
Returns 4 * find_fact(3) #no-1 = 4-1 -->3
3) find_fact(3)
Returns 3 * find_fact(2) #no-1 = 3-1 -->2
4) find_fact(2)
Returns 2 * find_fact(1) #no-1 = 2-1 -->1
5) find_fact(1)
Base case: Returns 1
Base case: The base case in recursion is a condition that stops the recursive calls.
Tasks:
strip()-Removes all white space characters (spaces, tabs, newlines) from the start and end of the string.
1) Remove unwanted spaces in front and back of the given string.
txt = " Today Is Friday "
start = 0
end = len(txt) - 1
while start < len(txt) and end >= 0:
i = start
while i < len(txt) and txt[i] == ' ':
i += 1
start = i
j = end
while j >= 0 and txt[j] == ' ':
j -= 1
end = j
break
result = txt[start:end+1]
print(result)
Output:
Today Is Friday
2) Reversing a number using recursive function:
def reverse_a_no(no,reverse = 0):
if no==0:
return reverse
rem = no%10
reverse = (reverse*10) + rem
no=no//10
return reverse_a_no(no,reverse)
no = int(input("Enter no. "))
reversed_no = reverse_a_no(no)
print(reversed_no)
Output:
Enter no. 15
51
3)Find prime number or not:
def find_prime(no,div=2):
if div<no:
if no%div == 0:
return False
div+=1
return find_prime(no,div)
else:
return True
no=int(input("Enter the number: "))
if find_prime(no):
print("EMIRP number")
else:
print("not EMIRP number")
Output:
1) Enter the number: 11
EMIRP number
2) Enter the number: 15
not EMIRP number
4) Find fibonacci:
def find_fibonacci(first_num,sec_num,no):
if first_num > no:
return
print(first_num, end=" ")
find_fibonacci(sec_num,first_num+sec_num,no)
no = int(input("Enter the number: "))
find_fibonacci(0,1,no)
Output:
Enter the number: 10
0 1 1 2 3 5 8
5. Find palindrome or not:
def palindrome(num,count=0):
if num == 0:
return count
return palindrome(num//10,count*10+num%10)
num=int(input("Enter the number:"))
result=palindrome(num)
if result==num:
print("Palindrome")
else:
print("Not palindrome")
Output:
Enter the number:121
Palindrome
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