Python exec built-in expression--exec ()

exec  obj
Function:
    EXEC executes python statements stored in a string or file, and can execute more complex Python code than eval,exec.  obj is the expression to execute.
The exec return value is always None.
Release Notes:* *  It is necessary to note that Exec is not a function in Python2, but a built-in statement (statement), but there is a execfile () function in Python 2. 

It can be understood that Python 3 consolidates the functionality of the EXEC statement and execfile () functions into a new EXEC () function.

Instance:

1>>>exec 'print "Hello World"'2 Hello World3 #single-line statement string4>>>exec "print ' runoob.com '"5 runoob.com6  7 #multi-line statement string8>>>exec """For I in range (5):9 ... print "ITER time:%d"% iTen ... """ One ITER time:0 AITER time:1 -ITER Time:2 -ITER Time:3 theITER Time:4

Example 2:

1x = 102Expr ="""3 z =4 sum = x + y + z5 print (sum)6 """7 deffunc ():8y = 209     exec(expr)Ten     exec(Expr, {'x': 1,'y': 2}) One     exec(Expr, {'x': 1,'y': 2}, {'y': 3,'Z': 4}) A      -Func ()

Results:

1 2 3 34

Python exec built-in expression--exec ()