[EMAIL PROTECTED] a écrit : > i was wondering if anyone could point me to some good reading about the > for and while loops
There's not much to say. while <expr>: <block> will execute <block> as long as <expr> is True. for <item> in <sequence>: <block> will execute <block> for each <item> in <sequence>. ie : for letter in ["a", "b", "c"]: do_something_with(letter) is equivalent to letter = "a" do_something_with(letter) letter = "b" do_something_with(letter) letter = "c" do_something_with(letter) > i am trying to write some programs > "Exercise 1 > > Write a program that continually reads in numbers from the user and > adds them together until the sum reaches 100. Since it's nearly impossible to predict how much iteration will be necessary for this condition to be satisfied[1], you want a while loop. The condition is 'the_sum >= 100' (starting with 'the_sum == 0'). The body of the loop is mainly : read a number in, add it to the_sum. [1] FWIW, we have 0 < number of iterations < +infinity, since nothing specifies that the user can not enter negative numbers !-) > Write another program > that reads 100 numbers from the user and prints out the sum. " Here you have a definite number of iterations, so it's a clear use case for a for loop, which will take care of the loop count by itself. Now since the for loop iterates over a sequence, you need such a sequence of 100 items. The canonical solution is the range(count) function, which will produce a sequence of <count> integers. The body of the loop is exactly the same as in the previous case. > but im not quite grasping those functions.. which 'functions' ? 'for .. in ..' and 'while ..' are statements (instructions), not functions. A functions is eval'd, and returns a value. A statement is executed, and has no value. HTH -- http://mail.python.org/mailman/listinfo/python-list
