Size of

The sizeof() operator evaluates to the size of a type in bytes. The sizeof operator (without the parentheses) evaluates to the size of a variable, object or expression in bytes. For example,

/* Type Sizes * sizeof.c * May 14 2007 */ #include int main(void) { double x; printf("On this machine, \n" "the size of an int is %d bytes,\n" "the size of x is %d bytes.\n", sizeof(int), sizeof x ); return 0; }

On this machine, the size of an int is 4 bytes, the size of x is 8 bytes.

Note that sizeof() takes a type, while sizeof takes a variable, object or expression. With some compilers, the two operators are interchangeable.

int type

An int type occupies one word of memory. One word is typically the size of a CPU register, making the int type the optimally efficient type. On 32-bit platforms, one word spans 4 bytes: