search

laszlodaniel / SmartBatteryHack

Arduino based hacking tool for smart batteries using SMBus.
GNU General Public License v3.0
149 stars 54 forks source link

a problem on define arrays in c++/arduino #7

Closed youxiaojie closed 4 years ago

youxiaojie commented 4 years ago

dear friend, I am not sure whether you make mistake in define array. uint16_t smbus_reg_dump_payload_length = 3*(smbus_reg_end - smbus_reg_start + 1) + 2; uint8_t smbus_reg_dump_payload[smbus_reg_dump_payload_length]; // max 770 bytes

what you mean is define a dynamic-size array? Using variable as size when defining array is not allowed in C, does it permit in arduino?

laszlodaniel commented 4 years ago

It's not permitted in Arduino either. I did this because after the function ends (leaves scope) this array is removed from memory and next time the function is called the array is created again. I like to first calculate the length in a separate variable and pass its value as the array length. Still it's a fixed value calculated once and it's not changing.

youxiaojie commented 4 years ago

I got it. In C99 standard it is ok. My book is 1996,and I have not used C for decades :( I am outdated.