eval用法

eval 函数的功能是将字符串生成语句执行。来看个简单的例子：

user_func = raw_input("type a function: y = ")
for x in range(1, 10):
    print "x = ", x, ", y = ", eval(user_func)

输入:

~ $ python eval_ex.py 
type a function: y = 1+2
x =  1 , y =  3
x =  2 , y =  3
x =  3 , y =  3
x =  4 , y =  3
x =  5 , y =  3
x =  6 , y =  3
x =  7 , y =  3
x =  8 , y =  3
x =  9 , y =  3
~ $