C++ Primer Plus

for Versus while

In C++ the for and while loops are essentially equivalent. For example, the for loop

for (init-expression; test-expression; update-expression){    statement(s)}

could be rewritten this way:

init-expression;while (test-expression){    statement(s)    update-expression;}

Similarly, the while loop

while (test-expression)    body

could be rewritten this way:

for ( ;test-expression;)    body

This for loop requires three expressions (or, more technically, one statement followed by two expressions), but they can be empty expressions (or statements). Only the two semicolons are mandatory. Incidentally, a missing test expression in a for loop is construed as true, so this loop runs forever:

for ( ; ; )    body

Because for loops and