# Write a program, which uses post-test loop, to compute the sum of a

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### #1 akash_9105

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• Posts: 31
• Joined: 04-April 08

# Write a program, which uses post-test loop, to compute the sum of a

Posted 24 October 2009 - 11:42 AM

Write a program, which uses post-test loop, to compute the sum of a series of numbers entered by the user. Note that the sum is displayed when the user enters the value 0, i.e. zero

Here is what i have done :

```i=0
sum=0.0
x=input("Enter a number : ")

while x!=0:
sum=x+sum
x=input("Enter a number : ")
i=i+1

if x==0:
print "sum is : ",sum

```

The code works fine but i am not being able to understand what is meant by a POST TEST LOOP . Can someone explain to me what is meant by a post test loop ?

thanx

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## Replies To: Write a program, which uses post-test loop, to compute the sum of a

### #2 Tshiknn

Reputation: 4
• Posts: 20
• Joined: 18-October 09

## Re: Write a program, which uses post-test loop, to compute the sum of a

Posted 24 October 2009 - 08:06 PM

A normal loop checks the conditional, then if found true, runs the code. Then it goes back to the conditional and repeats. A post-test loop is a loop that runs the code, then checks the condition, then if found true, runs the code again. The difference is that a post-test loop is always runs the code once, even if the conditional isn't true, whereas a pre-test loop doesn't run the code if the conditional isn't true. Here's the basic form for a post-test loop:

```# post-test loop
while True:
<statements>
if not <conditional>:
break

# pre-test loop
while <conditional>:
<statements>
```

You don't often use post-test loops, but sometimes they're useful.

### #3 akash_9105

Reputation: 0
• Posts: 31
• Joined: 04-April 08

## Re: Write a program, which uses post-test loop, to compute the sum of a

Posted 24 October 2009 - 09:32 PM

Thanx for your quick response, so even though my code is working, is it a post test loop ?

Here is my code:
```
i=0
sum=0.0
x=input("Enter a number : ")

while x!=0:
sum=x+sum
x=input("Enter a number : ")
i=i+1

if x==0:
print "sum is : ",sum

```

Tshiknn, on 24 Oct, 2009 - 07:06 PM, said:

A normal loop checks the conditional, then if found true, runs the code. Then it goes back to the conditional and repeats. A post-test loop is a loop that runs the code, then checks the condition, then if found true, runs the code again. The difference is that a post-test loop is always runs the code once, even if the conditional isn't true, whereas a pre-test loop doesn't run the code if the conditional isn't true. Here's the basic form for a post-test loop:

```# post-test loop
while True:
<statements>
if not <conditional>:
break

# pre-test loop
while <conditional>:
<statements>
```

You don't often use post-test loops, but sometimes they're useful.

### #4 Tshiknn

Reputation: 4
• Posts: 20
• Joined: 18-October 09

## Re: Write a program, which uses post-test loop, to compute the sum of a

Posted 25 October 2009 - 10:11 AM

No, not really. A post test loop would be an infinite loop that runs the code, then breaks if the conditional isn't true. A post-test loop would look like this in your program:

```i=0
sum=0.0
x=input("Enter a number : ")

while True:
sum=x+sum
x=input("Enter a number : ")
i=i+1

if x==0:
print "sum is : ", sum
break
```