while（）和for（）之间有什么区别？ [重复]

Question

This question already has an answer here:

• Differences between a while loop and a for loop in PHP? 5 answers

Maybe my question seems primary, But actually it is not. I claim that I can do everything is done with for() by while(), And conversely. So really when while() is useful when there is for()? I need to a example that I can do that by for() and I can not do that by while(). There is? I think there is not ...!

Here is the structure:

for (init counter; test counter; increment counter) {
    code to be executed;
}


init counter;
while (test counter) {
    code to be executed;
    increment counter;
}

see? they are exactly the same, Now I want to know why php has both of them?

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Answer 1

The difference is that the do while loop executes at least once because it checks for the loop condition while exiting. While is a entry controlled loop and do while is a exit control loop. Whereas in do while loop it will enter the loop and will then check for the condition.

while loop - used for looping until a condition is satisfied and when it is unsure how many times the code should be in loop

for loop - used for looping until a condition is satisfied but it is used when you know how many times the code needs to be in loop

do while loop - executes the content of the loop once before checking the condition of the while.