Python 初體驗（八）

編寫簡單指令碼：

you draw n random uniformly distributed numbers, where n is given on the command line, and compute the average of these numbers.

the lesson learned from this little prctice can be concluded as:

1. generation of random number
2. read parameter from command line with sys.argv
3. application of regular expression in Python

import sysimport randomimport reif len(sys.argv) != 2:    print 'invalid parameter input'    sys.exit()pattern = re.compile(r'^\d+$')match = pattern.match(sys.argv[1])if match:    b=[]    a = int(sys.argv[1])    while(a != 0):        b.append(random.uniform(-1,1))        print '%.4f' % b[-1]        a -= 1    average = sum(b)/len(b)    print 'Average: %.4f' % averageelse:    print 'invalid parameter input'    sys.exit()