change a list of integer into a list of strings and for loop & string

[python101]

I have a list of integers s=[1,2,3,4] to be converted to s=['1','2','3','4']
I tried

s=[1,2,3,4]
 
for i in s:
    str(a[i])
 
 
'2'
'3'
'4'
 

but I lost "1" , can someone explain why I lost "1"? I knew that I could use

   str(a[i-1])
 

My second question is about create a new string

# I have a string
s='hello! world'
 
# now I want to have a new string printed as
#h
#he
#hel
#...
 
# I tried
 
for i in len(s):
 stringA=a[i]
 stringA+=a[i+1]
 print stringA
#but it did not work
 
 

[rhitam30111985]

I have a list of integers s=[1,2,3,4] to be converted to s=['1','2','3','4']
I tried

s=[1,2,3,4]
 
for i in s:
    str(a[i])
 
 
'2'
'3'
'4'
 

but I lost "1" , can someone explain why I lost "1"? I knew that I could use

   str(a[i-1])
 

replace a[i] with i... i means the the elements in the list... not their index.. :

for i in s:
          str(i)
 

[ghostdog74]

>>> s=[1,2,3,4]
>>> [str(i) for i in s]
['1', '2', '3', '4']
>>> s=[str(i) for i in s]
 

[python101]

thank you very much.

I just added second question.

[rhitam30111985]

for the hello world program u can try this :

 for  i in range(len(s)):
     print s[0:i+1]
 

[python101]

i just read the book some days ago that I could use [:::] to get this.

Thank you very much for helping me out.

[rhitam30111985]

for i in len(s):

stringA=a[i]

stringA+=a[i+1]

print stringA

your code did not work because u havent defined the variable 'a' anywhere.... so the interpreetr doesnt know what to assign to the variable 'stringA'

regards
rhitam