In simple Python:
s= 'Hello, World!'
codeList = list()
for c in s:
codeList.append(ord(c))
print codeList
if len(codeList)%2 > 0:
codeList.append(0)
finalList = list()
for d in range(0,len(codeList)-1, 2):
finalList.append(codeList[d]*256+codeList[d+1])
print finalList
If you use list comprehensions:
s= 'Hello, World!'
codeList = [ord(c) for c in s]
if len(codeList)%2 > 0: codeList.append(0)
finalList = [codeList[d]*256+codeList[d+1] for d in range(0,len(codeList)-1,2)]
print codeList
print finalList