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authorGuido van Rossum <guido@python.org>1997-03-25 18:25:20 (GMT)
committerGuido van Rossum <guido@python.org>1997-03-25 18:25:20 (GMT)
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Added two new questions about number conversions.
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index 8bd9991..32a49a8 100644
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@@ -182,6 +182,8 @@ Here's an overview of the questions per chapter:
4.41. Q. How do I delete a file? And other file questions.
4.42. Q. How to modify urllib or httplib to support HTTP/1.1?
4.43. Q. Unexplicable syntax errors in compile() or exec.
+ 4.44. Q. How do I convert a string to a number?
+ 4.45. Q. How do I convert a number to a string?
5. Extending Python
5.1. Q. Can I create my own functions in C?
@@ -1708,6 +1710,27 @@ compile(), exec or execfile(), it *must* end in a newline. In some
cases, when the source ends in an indented block it appears that at
least two newlines are required.
+4.44. Q. How do I convert a string to a number?
+
+A. To convert, e.g., the string '144' to the number 144, import the
+module string and use the string.atoi() function. For floating point
+numbers, use string.atof(); for long integers, use string.atol(). See
+the library reference manual section for the string module for more
+details. While you could use the built-in function eval() instead of
+any of those, this is not recommended, because someone could pass you
+a Python expression that might have unwanted side effects (like
+reformatting your disk).
+
+4.45. Q. How do I convert a number to a string?
+
+A. To convert, e.g., the number 144 to the string '144', use the
+built-in function repr() or the backquote notation (these are
+equivalent). If you want a hexadecimal or octal representation, use
+the built-in functions hex() or oct(), respectively. For fancy
+formatting, use the % operator on strings, just like C printf formats,
+e.g. "%04d" % 144 yields '0144' and "%.3f" % (1/3.0) yields '0.333'.
+See the library reference manual for details.
+
5. Extending Python
===================