1. 一般格式化输出记得加括号, 且无逗号 print "%d" % (variable)
2. print "hello" 自带\n
3. print "hello", 加上逗号之后，不会换行，但会加一个空格
4. 如果print加逗号不换行的话会有一个空格 而sys.stdout.write()就没有；
5. %r是一个万能的格式付，它会将后面给的参数原样打印出来，带有类型信息。
python print %r 案例
formatter = "%r %r %r %r"
print formatter % (1, 2, 3, 4)
print formatter % ("one", "two", "three", "four")
print formatter % (True, False, False, True)
print formatter % (formatter, formatter, formatter, formatter)
print formatter % (
"I had this thing.",
"That you could type up right.",
"But it didn't sing.",
"So I said goodnight."
)
