C pointer arithmetic while subtracting - 


int a[ ] ={1,3,5,7,9,11,13,15,17,19};     int *pa = &a[4],*pb = &a[1];

what value of pa-pb? ans: 3, how? shouldn't 12 (like printed pa , pb too, double check, , got 12)?

pointer arithmetic different normal arithmetic. in pointer arithmetic a-1, a pointer doesn't mean value of a subtracted 1. means go 1 unit of memory.

in example, pa-pb doesn't mean value of pa-pb. 1 int variable requires 4 bytes pa-pb means go 3 int's reach pb pa.

for int 1 unit of memory 4 bytes, float 8 bytes, char 1 byte. note: these value changes system system, these value.


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