Core Python Programming (2nd Edition)

6-12. Strings.
a.
b.
c.
Create a function called findchr(), with the following declaration:
def findchr(string, char)
findchr() will look for character char in string and return the index of the first
occurrence of char, or -1 if that char is not part of string. You cannot use
string.*find() or string.*index() functions or methods.
Create another function called rfindchr() that will find the last occurrence of a
character in a string. Naturally this works similarly to findchr(), but it starts its
search from the end of the input string.
Create a third function called subchr() with the following declaration:
def subchr(string, origchar, newchar)
subchr() is similar to findchr() except that whenever origchar is found, it is
replaced by newchar. The modified string is the return value.
6-13. Strings. The string module contains three functions, atoi(), atol(), and atof(), that
convert strings to integers, long integers, and floating point numbers, respectively. As
of Python 1.5, the Python built-in functions int(), long(), and float() can also
perform the same tasks, in addition to complex(), which can turn a string into a
complex number. (Prior to 1.5, however, those built-in functions converted only
between numeric types.)
An atoc() was never implemented in the string module, so that is your task here. atoc
() takes a single string as input, a string representation of a complex number, e.g., '-
1.23e+4-5.67j', and returns the equivalent complex number object with the given
value. You cannot use eval(), but complex() is available. However, you can only use
complex() with the following restricted syntax: complex(real, imag) where real and
imag are floating point values.