How do I get the size of C instruction ? -

how size of c instruction? example want know, if working on windows xp intel core2duo processor, how space instruction:

 while(1==9)  {   printf("test"); }    

takes?

c not have notion of "instruction", let alone notion of "size of instruction", question doesn't make sense in context of "programming in c".

the fundamental element of c program statement, can arbitrarily complex.

if care details of implementation, inspect machine code compiler generates. 1 broken down in machine instructions, , can see how many bytes required encode each instruction.

for example, compile program

#include <cstdio> int main() { (;;) std::printf("test"); } 

with

g++ -c -o /tmp/out.o /tmp/in.cpp 

and disassemble with

objdump -d /tmp/out.o -mintel 

and get:

00000000 <main>:    0:   55                      push   ebp    1:   89 e5                   mov    ebp,esp    3:   83 e4 f0                ,    esp,0xfffffff0    6:   83 ec 10                sub    esp,0x10    9:   c7 04 24 00 00 00 00    mov    dword ptr [esp],0x0    10:   e8 fc ff ff ff          call   11 <main+0x11>    15:   eb f2                   jmp    9 <main+0x9> 

as can see, call instruction requires 5 bytes in case, , jump loop requires 2 bytes. (also note conspicuous absence of ret statement.)

you can instruction in your favourite x86 documentation , see e8 single-byte call opcode; subsequent 4 bytes operand.