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#include <assert.h>
#include <stddef.h>
int main(int argc, char *argv[])
{
// Test reading from an array using a pointer
int a[3]={1, 2, 3};
int *p=a;
assert(p==&a[0]);
assert(*p==1);
// Test pointer arithmetic
int *q=&a[1];
assert(q==p+1);
assert(*q==2);
// Test pointer diffs
ptrdiff_t x=1;
assert(q-p==x);
// Test writing into an array using a pointer
*q=4;
assert(a[1]==4);
a[1]=2;
// We now explore pointers and indexes each with more than one possible value
int *r=&a[1];
int b[3]={0, 0, 0};
int *s=&b[1];
int i=1;
if (argc>2)
{
r=&a[2];
s=&b[2];
i=2;
}
// Test reading from an array using a pointer with more than one possible
// value
assert(*r==2);
assert(*r==1);
assert(*s==0);
assert(*s==1);
// Test pointer arithmetic with an unknown index
int *t=&a[i];
assert(t==p+i);
// Test pointer diffs with an unknown index
ptrdiff_t y=i;
assert(t-p==y);
// Test writing into an array using a pointer with an unknown index
*r=5;
assert(a[i]==5);
assert(a[1]==5);
return 0;
}
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