Question

I have a class in system-C with some data members as such:

long double x[8]; 

I’m initializing it in the construction like this:

for (i = 0; i < 8; ++i) {     x[i] = 0; } 

But the first time I use it in my code I have garbage there.

Because of the way the system is built I can’t connect a debugger easily. Are there any methods to set a data breakpoint in the code so that it tells me where in the code the variables were actually changed, but without hooking up a debugger?

Answer 1

You could try starting a second thread which spins, looking for changes in the variable:

 #include <pthread.h>  void *ThreadProc(void *arg) {   volatile long double *x = (volatile long double *)arg;   while(1)   {     for(int i = 0; i < 8; i++)     {       if(x[i] != 0)       {         __asm__ __volatile__ ('int 3');  // breakpoint (x86)       }   }    return 0;  // Never reached, but placate the compiler } ... pthread_t threadID; pthread_create(&threadID, NULL, ThreadProc, &x[0]); 

This will raise a SIGTRAP signal to your application whenever any of the x values is not zero.