for Loops

Typical case:
for (i = 0; i < len; i++) {
Atypical cases
- for ( i = 0; i <= extrknt; i++ )
- for (i = 1; i < month; i++)
- for (i = 1; i <= nargs; i++)
- for (code = 255; code >= 0; code--) {
Library function loops:
    if ((dd = opendir(dir)) == NULL)
        return (CC_ERROR);
    for (dp = readdir(dd); dp != NULL; dp = readdir(dd)) {
Use of multiple expressions:
for (cnt = 1, t = p; cnt <= cnt_orig; ++t, ++cnt) {
Infinite loop:
    for (;;) {
        s = (state_t) (*s)();
        quiet = 0;
    }