char* getWeekDayStr(uint8_t weekDay) {
static const char* tbl[7] = { "Sat",
"Sun",
"Mon",
"Tue",
"Wed",
"Thu",
"Fri",
};

return tbl[weekDay];
}
これのreturnの行で「!」が付くんだけどなんで?
TrueStudioです。