string - getting the last 9 digits of a char buffer in Arduino -

in previous code of mine, using following line of code last 9digits of "command" string

if(command.indexof("kitchen light: set top color") >=0)  {oncolorvaluered = (command.charat(28)- 48)*100 + (command.charat(29)- 48)*10 + (command.charat(30)- 48);} 

now using char buffer (char packetbuffer[udp_tx_packet_max_size];) , using above code not work since packetbuffer not string, how please go this

try defining function search string

int indexof_for_char(const char *str, int str_length, const char *target) {     // naive method     (int index = 0; index < str_length; index++) {         int j;         // check if matched         (j = 0; target[j] != '\0' && index + j < str_length && str[index + j] == target[j]; j++);         // if matched, return index         if (target[j] == '\0') return index;     }     return -1; } 

and using subscripting.

if(indexof_for_char(packetbuffer, udp_tx_packet_max_size, "kitchen light: set top color") >=0)  {oncolorvaluered = (packetbuffer[28]- 48)*100 + (packetbuffer[29]- 48)*10 + (packetbuffer[30]- 48);}