c - Why do I have to use %ld when referring to the size of an int variable? -

i define int this:

int a; 

when want lookup size of int, have use format specifier %ld this:

printf("int size %ld\n", sizeof(a)); 

when use %d format specifier, following error:

foo.c:7:10: warning: format ‘%d’ expects argument of type ‘int’, argument 2 has type ‘long unsigned int’ [-wformat=]     printf("int size %d\n", sizeof(a)); 

the question is, why result of sizeof() defined long unsigned int when parameter of function int?

the type of sizeof(anything) size_t, unsigned integral constant. print it, should using %zu.