Actually Understanding Programming Helps

import timeit
from array import array
numAdd = 1 #Additional changes are needed when numAdd = 1000000
totalMemory = 1000000 # bytes

#global concatString # global ensures a slow-down under Linux
addString = ""
for i in range(0, numAdd):
 addString = addString + "1"

char_array = array('c')

# First part: in-memory
numIter = int(totalMemory / len(addString))
f = open('test.txt','w')
start = timeit.default_timer()
for i in range(0, numIter):
# concatString = addString + concatString # modified: concatString = concatString + addString
  char_array.fromstring("1");
stop = timeit.default_timer()
stringTime = stop - start
start = timeit.default_timer()
f.write(char_array.tostring())
f.flush()
f.close()
stop = timeit.default_timer()
fileTime = stop - start
print "in-memory: String took " + str(stringTime) + ", file took " + str(fileTime)

# second part: disk-only
numIter = int(totalMemory / len(addString))
f = open('test.txt','w')
start = timeit.default_timer()
for i in range(0, numIter):
 f.write(addString)
f.flush()
f.close()
stop = timeit.default_timer()
fileTime = stop - start
print "disk-only: file took " + str(fileTime)