o_18ufhmfmq19t513t3lgmn5l1qa8a.pdf

APPENDIX B ■ PYTHON REFERENCE 569
The global Statement
The global statement is used to mark a variable as global. It is used in functions to allow statements
in the function body to rebind global variables. Using the global statement is generally
considered poor style and should be avoided whenever possible.
Example:
count = 1
def inc():
global count
count += 1
The exec Statement
The exec statement is used to execute strings containing Python statements, optionally with a
given global and local namespace (dictionaries).
Examples:
exec 'print "Hello, world!"'
exec 'x = 2' in myglobals, mylocals # ... where myglobals and mylocals are dicts
Compound Statements
Compound statements contain groups (blocks) of other statements.
The if Statement
The if statement is used for conditional execution, and it may include elif and else clauses.
Example:
if x < 10:
print 'Less than ten'
elif 10