摘要：
len is a build-in function that returns the numbers of characters in a string: Since we started counting at zero, the last index should be 5... 阅读全文
摘要：
A string is a sequence of characters. You can access the characters one at a time with the bracket operator. The second statement selects ch... 阅读全文
摘要：
Loops are often used in programs that compute numerical results by starting with an approximate answer and iteratively improving it.For example, one w... 阅读全文