How do you Make A Repeat-Until Loop in C++?

问题

How do you Make A Repeat-Until Loop in C++? As opposed to a standard While or For loop. I need to check the condition at the end of each iteration, rather than at the beginning.

回答1:

do
{
  //  whatever
} while ( !condition );

回答2:

When you want to check the condition at the beginning of the loop, simply negate the condition on a standard while loop:

while(!cond) { ... }

If you need it at the end, use a do ... while loop and negate the condition:

do { ... } while(!cond);

回答3:

You could use macros to simulate the repeat-until syntax.

#define repeat do
#define until(exp) while(!(exp))

回答4:

For an example if you want to have a loop that stopped when it has counted all of the people in a group. We will consider the value X to be equal to the number of the people in the group, and the counter will be used to count all of the people in the group. To write the

while(!condition)

the code will be:

int x = people;

int counter = 0;

while(x != counter)

{

counter++;

}

return 0;

回答5:

Just use:

do
{
  //enter code here
} while ( !condition );

So what this does is, it moves your 'check for condition' part to the end, since the while is at the end. So it only checks the condition after running the code, just like how you want it

回答6:

Repeat is supposed to be a simple loop n times loop... a conditionless version of a loop.

#define repeat(n) for (int i = 0; i < n; i++) 

repeat(10) {
    //do stuff
}

you can also also add an extra barce to isolate the i variable even more

#define repeat(n) { for (int i = 0; i < n; i++) 
#define endrepeat }

repeat(10) {
    //do stuff
} endrepeat;

[edit] Someone posted a concern about passing a something other than a value, such as an expression. just change to loop to run backwards, causing the expression to be evaluated only once

#define repeat(n) { for (int i = (n); i > 0; --i)

来源：https://stackoverflow.com/questions/1077216/how-do-you-make-a-repeat-until-loop-in-c

标签

c++

loops

for-loop

while-loop