Enter the sum of n numbers using file

n=int(raw_input('Enter the n for sum of n numbers: '))
f=open('integers.txt','w')
for count in range(n+1):
      f.write(str(count)+"\n")
f.close()

f=open('integers.txt','r')
sum=0
for l in f:
      l=l.strip()
      number=int(l)
      sum+=number
print 'The sum is',sum

Writing and reading integers from a file

f=open('myfile.txt','w')
for count in  range(5):
      f.write(str(count))
f.close()
f=open('myfile.txt','r')
t=f.read()
print t

Writing and reading string from a file

f=open('myfile.txt','w')
f.write('\n Image Processing Research Group \n www.iprg.co.in \n')
f.close()
f=open('myfile.txt','r')
text=f.read()
print text

Basic operations in Python List

l=[]
n=int(raw_input('Enter the no of elements added to list:'))
for i in range(n):
      element=int(raw_input('Enter the elements:'))
      l.append(element)
print '\nNew List is ',
m=int(raw_input('\nEnter the no of elements added to list using insert:'))
for i in range(m):
      u=int(raw_input('Enter the index to be added'))
      u1=int(raw_input('Enter the element to be added'))
      l.insert(u,u1)
print '\nNew List after insert operation is:   ',l
ch=int(raw_input('\nPress 1 to pop the last element\nPress 2 to pop the element in a particular index\nEnter the choice: '))
if ch==1:
 l.pop()
 print '\nNew List after deletion is: ',l
elif ch==2:
 p=int(raw_input('Enter the element index to be deleted'))
 l.pop(p)
 print '\nNew List after deletion is: ',l
else:
  print '\nInvalid choice'
print ' \nList elements are sorted:  ',l

To add elements in list using insert

y=[]
n=int(raw_input('Enter the no of elements added to list:'))
index=0
for i in range(n):
      element=int(raw_input('Enter the elements:'))
      y.insert(index, element)
      index=index+1
print y