Question

Anyone have any idea why this works:

int main(void)
{
char action;
int *i;
*i=10;
printf("%d",*i);
action='C';
printf("%c",action);
}

but this doesnt

int main(void)
{
char action='C';
int *i;
*i=10;
printf("%d",*i);
printf("%c",action);
}

I am getting no errors but it will not run! cant see why that little difference makes it crash

Answer 1

It’s undefined bahavior.
You have created a pointer and without initializing the pointer, you are directly putting the value 10 to the memory location pointed to by pointer i where i has indeterminate value.So, in that case it will put the value 10 to that garbage value location (the value of pointer i). So it may execute if garbage value location is accessible or may crash if memory location is not accessible.

Hence it’s just undefined bahavior