Why there is no do while loop in python

Question

Why doesn't Python have a 'do while' loop like many other programming language, such as C?

Example : In the C we have do while loop as below :

do {    statement(s); } while( condition ); 

Answer 1

There is no do...while loop because there is no nice way to define one that fits in the statement: indented block pattern used by every other Python compound statement. As such proposals to add such syntax have never reached agreement.

Nor is there really any need to have such a construct, not when you can just do:

while True:     # statement(s)     if not condition:         break 

and have the exact same effect as a C do { .. } while condition loop.

See PEP 315 -- Enhanced While Loop:

Rejected [...] because no syntax emerged that could compete with the following form:

    while True:         <setup code>         if not <condition>:             break         <loop body> 

A syntax alternative to the one proposed in the PEP was found for a basic do-while loop but it gained little support because the condition was at the top:

    do ... while <cond>:         <loop body> 

or, as Guido van Rossum put it:

Please reject the PEP. More variations along these lines won't make the language more elegant or easier to learn. They'd just save a few hasty folks some typing while making others who have to read/maintain their code wonder what it means.

Answer 2

Because everyone is looking at it wrong. You don't want DO ... WHILE you want DO ... UNTIL.

If the intitial condition is true, a WHILE loop is probably what you want. The alternative is not a REPEAT ... WHILE loop, it's a REPEAT ... UNTIL loop. The initial condition starts out false, and then the loop repeats until it's true.

The obvious syntax would be

repeat until (false condition):   code   code 

But for some reason this flies over everyone's heads.