Thread: very strange passing of arguments

Hi everyone,

something very strange is happening in a very simple code;
specifically, I have this function:

Code:

void flinspace(float vmin, float vmax, int n, float *VECT)
{
	//!!! VECT must be allocated starting from 1 for this function to work properely
	
	int i;
	float dv;
	
        // WARNING NOTE THIS PRINTING LINE!!!
	//printf("vmin = %f  vmax =%f\n", vmin, vmax);
	
        VECT[1] = vmin;
	for (i=2; i<=n; i++){
		dv = (vmax - vmin)/(n-1);
		VECT[i] = VECT[i-1] + dv;
	}

return;
}

now, this function is called by a main function that passes the correct arguments to it as expected. However, here is the very strange behavior:

although argument 1 and 2 (float vmin, float vmax) are not supposed to be modified within this function, once I comment the "printf" line above (see WARNING NOTE above), vmin and vmax ARE in fact modified randomly within this function, and are returned to the calling function with a different value from what they were assigned;
on the other hand, when I UNcomment the print line, everythign stands still, and the only variable that is returned with a new value is the expected/wanted VECT.

Is anyone able to help me understand how this is possible?
I am on a Mac OSX 10.5 with GCC 4.0.1

Thank you in advance

Hi, thanks for replying and trying to help.

I indeed freed some memory from space that was not allcoated. I was allocating certain previous arrays with npts elements without noticing that npts was never assigned beforehand.

Thank you again; It was too strange to be real!