#### 8.5.1 The Uses of the Comma Operator ¶

With commas, you can put several expressions into a place that allows one expression—for example, in the header of a `for` statement. This statement

    for (i = 0, j = 10, k = 20; i < n; i++)

contains three assignment expressions, to initialize `i`, `j` and `k`. The syntax of `for` requires just one expression for initialization; to include three assignments, we use commas to bundle them into a single larger expression, `i = 0, j = 10, k = 20`. This technique is also useful in the loop-advance expression, the last of the three inside the `for` parentheses.

In the `for` statement and the `while` statement (see Loop Statements), a comma provides a way to perform some side effect before the loop-exit test. For example,

    while (printf ("At the test, x = %d\n", x), x != 0)