c++ - Why to specify a pointer type? -

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this question has answer here:

what happens while declaring pointer of specific type? there use specify type pointer other pointer arithmetic or indexing?

type of pointer needed in following situations

  • dereferencing pointer
  • pointer arithmetic

here example of dereferencing pointer.

{     char *ptr; //pointer of type char     short j=256;     ptr=&j;    // have ignore warnings     printf("%d",*ptr) }

now because ptr of type char read 1 byte. binary value of 256 0000000100000000 because ptr of type char read first byte hence output 0.

note: if assign j=127 output 127 because 127 hold first byte.

now, example of pointer arithmetic:

{     int *ptr;     int var=0;     ptr=&var;     var++;     ptr++;// pointer arithmetic }

are statements var++ , ptr++ same thing? no, var++ means var=var+1 , ptr++ means ptr=ptr+4. because compiler "knows" pointer , points int, adds 4 ptr instead of 1, pointer "points to" next integer.


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