I would like to report an intriguing bug I have. The piece of code below is supposed to print out 20 times "1.0". Instead, when compiling with icc (11.1) on my mac (snow leopard 10.6.8), I get unstable values (16 times "0.0" then 4 times "1.0"). I make use of several features in the code but none of them seems to have a bad syntax (no error during compilation, and valgrind reports no error during running). However if I change anything (even non used function - that's why I find it very strange), I get the correct output. Compiling with gcc gives the correct output as well.
But I think the strangest thing is that if I delete the function "function1", the bug disappears, although the function is NOT used in the code.
This is really odd, and now I fear that my code (which is much bigger than that) will be unstable. I need your help, I'm really puzzled by this. Is there anything wrong in the syntax?
main.c:
#include "main.h"
int main(argc,argv)
int argc;
char **argv;
{
Config para;
para.option1 = ONE;
para.a[0] = 0.0;
para.a[1] = 0.0;
para.a[2] = 0.0;
para.a[3] = 1.0;
int i;
double *x = (double *)malloc(20*sizeof(double));
for(i=0;i<20;i++) x[i] = 1.0;
for(i=0;i<20;i++) printf("%f \n", x[i]);
free(x);
function2(para);
return EXIT_SUCCESS;
}
void function1(int option){
switch(option){
case ONE: case TWO: case THREE: case MONE:
printf("MONE to THREE\n");
break;
case FOUR:
printf("FOUR\n");
break;
}
return;
}
void function2(const Config para){
if(para.option1 == FOUR){
printf("FOUR\n");
}
return;
}
main.h:
#include <string.h>
#include <stdio.h>
#include <stddef.h>
#include <math.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <stdarg.h>
#define MONE -1
#define ONE 1
#define TWO 2
#define THREE 3
#define FOUR 4
typedef struct Config
{
int option1, option2;
double a[4];
} Config;
void function1(int option);
void function2(const Config para);
