Is there ever a need for a “do {…} while ( )” loop?

Question

Bjarne Stroustrup (C++ creator) once said that he avoids \"do/while\" loops, and prefers to write the code in terms of a \"while\" loop instead. [See quote below.]

S

Answer 1

This is cleanest alternative to do-while that I have seen. It is the idiom recommended for Python which does not have a do-while loop.

One caveat is that you can not have a continue in the since it would jump the break condition, but none of the examples that show the benefits of the do-while need a continue before the condition.

while (true) {
       
       if (!condition) break;
       
}

Here it is applied to some of the best examples of the do-while loops above.

while (true);  {
    printf("enter a number");
    scanf("%c", &c);
    if (!(c < '0' ||  c > '9')) break;
} 

This next example is a case where the structure is more readable than a do-while since the condition is kept near the top as //get data is usually short yet the //process data portion may be lengthy.

while (true);  {
    // get data 
    if (data == null) break;
    // process data
    // process it some more
    // have a lot of cases etc.
    // wow, we're almost done.
    // oops, just one more thing.
}