Strings with zero-padded values and other string formatting examples in Python

Assume you want to convert a number to a string but you want to pad the smaller numbers with zeros so that all strings have the same length (for example, '0009', '0069' and '0132'). There are many ways to do this but in Python, there is a very elegant way using string formatting:

anumber = 9
thestr = "%04d" % (anumber)
print thestr
0009

anumber = 69
thestr = "%04d" % (anumber)
print thestr
0069

anumber = 132
thestr = "%04d" % (anumber)
print thestr
0132

anumber = 12541
thestr = "%04d" % (anumber)
print thestr
12541

Since the format() function is preferred (since Python 2.6 I think), you might want to use it instead (see here):

anumber = 69
thestr = "{0:0>4}".format(anumber)
print thestr
0069

thestr = "{0:0<4}".format(anumber)
print thestr
6900

thestr = "{0:0<8}".format(anumber)
print thestr
69000000

thestr = "{0:0^8}".format(anumber)
print thestr
00069000

thestr = "{0:-^8}".format(anumber)
print thestr
---69---