Thread: Payload modification - If or initiation problem

Hi,

I want to change N-th byte of payload. This code works but does not do what I want. I see that a-th byte of payload is set to 0xAA. What I am doing wrong here?

Code:

unsigned char data[4]={0x00,0x00,0x01,0xb3};
int a=55;
 int k = 0;
//int j;
int N = 51;
while(k < m->data_len) {

 
    if (m->payload[k] != 0x00) {
        k++;
                       }
    else {
    if (memcmp(&m->payload[k],data,sizeof(data))==0) {
int j;
if(j % N == 0) { 
m->payload[a]=0xAA;     
m->payload[j]=0xFF; // ??????

}
     else {break;} 
 j++;                         } 
else {
k++;   }
     }
                  }