segmentation fault in a C code - linux

Question

I have written a C code yesterday which works fine. Now I want to make some changes in the file, so I just copy this code in a new file. Compilation of new file is just fine, but when I try to run my executable file, I am getting segmentation fault. However my previous code is working. Initially I thought it's a permission issue so I change the permission of executable using chmod 777. But still I am getting segmentation fault. Here is my code:-
#include <stdio.h>
#include <time.h>
void pauseSec(int sec);
int main() {
FILE *io,*iodir,*ioval,*iodir_S,*ioval_S,*io_S,*iodir_P,*ioval_P,*io_P;
io = fopen("/sys/class/gpio/export", "w");
fseek(io,0,SEEK_SET);
fprintf(io,"%d",15);
fflush(io);
iodir = fopen("/sys/class/gpio/gpio15/direction", "w");
fseek(iodir,0,SEEK_SET);
fprintf(iodir,"out");
fflush(iodir);
while(1)
{
fprintf(ioval,"%d",1);
fflush(ioval);
pauseSec(1);
fprintf(ioval,"%d",0);
fflush(ioval);
pauseSec(1);
}
fclose(io);
fclose(iodir);
fclose(ioval);
return 0;
}
void pauseSec(int sec) {
time_t now,later;
now = time(NULL);
later = time(NULL);
while((later - now) < (double)sec)
later = time(NULL);
}
I wonder why same code is behaving differently when written in two different file. What can be the reason for this?

Answer 1

Got the issue, forget to initialize ioval. Correct code is here:-
#include <stdio.h>
#include <time.h>
void pauseSec(int sec);
int main() {
FILE *io,*iodir,*ioval,*iodir_S,*ioval_S,*io_S,*iodir_P,*ioval_P,*io_P;
io = fopen("/sys/class/gpio/export", "w");
fseek(io,0,SEEK_SET);
fprintf(io,"%d",15);
fflush(io);
iodir = fopen("/sys/class/gpio/gpio15/direction", "w");
fseek(iodir,0,SEEK_SET);
fprintf(iodir,"out");
fflush(iodir);
ioval = fopen("/sys/class/gpio/gpio15/value", "w");
while(1)
{
fprintf(ioval,"%d",1);
fflush(ioval);
pauseSec(1);
fprintf(ioval,"%d",0);
fflush(ioval);
pauseSec(1);
}
fclose(io);
fclose(iodir);
fclose(ioval);
return 0;
}
void pauseSec(int sec) {
time_t now,later;
now = time(NULL);
later = time(NULL);
while((later - now) < (double)sec)
later = time(NULL);
}