What is the difference between %p and %d in C language?

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  • Which means the memory address that appears with %p and the %d exactly?
  • What’s the difference?
int main()
{
    int teste = 10;
    int *ptr = &teste;

    printf("%p\n%d",ptr, ptr);

    return 0;
}
c pointer memory formatting printf

1 answer

5


The correct way to print a pointer is the %p. Some compilers require you to make a cast for void *. Documentation.

Some implementations and depending on the compiler configuration allow using the %d directly since it is known that a pointer can be converted to an integer, others only leave if you make a cast for a whole, since the %d is the placeholder for integers and not for pointers.

If you use the %p the printed value takes into account that it is a memory address and prints in the most appropriate way possible, so it should be in hexadecimal notation which is easier to evaluate an address. If you use the %d the address will be printed as a decimal number, which can be more difficult to interpret as an address, mixing concepts. The number is the same, only the way of presenting differs.

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