Doubts in executable and relocatable object file
<p>Hello, I have written a simple Hello World program.</p>
<pre><code> #include <stdio.h>
int main() {
printf("Hello World");
return 0;
}
</code></pre>
<p>I wanted to understand how the relocatable object file and executable file look like. The object file corresponding to the main function is</p>
<pre><code>0000000000000000 <main>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: bf 00 00 00 00 mov $0x0,%edi
9: b8 00 00 00 00 mov $0x0,%eax
e: e8 00 00 00 00 callq 13 <main+0x13>
13: b8 00 00 00 00 mov $0x0,%eax
18: c9 leaveq
19: c3 retq
</code></pre>
<p>Here the function call for printf is callq 13. One thing i don't understand is why is it 13. That means call the function at adresss 13, right??. 13 has the next instruction, right?? Please explain me what does this mean??</p>
<p>The executable code corresponding to main is</p>
<pre><code>00000000004004cc <main>:
4004cc: 55 push %rbp
4004cd: 48 89 e5 mov %rsp,%rbp
4004d0: bf dc 05 40 00 mov $0x4005dc,%edi
4004d5: b8 00 00 00 00 mov $0x0,%eax
4004da: e8 e1 fe ff ff callq 4003c0 <printf@plt>
4004df: b8 00 00 00 00 mov $0x0,%eax
4004e4: c9 leaveq
4004e5: c3 retq
</code></pre>
<p>Here it is callq 4003c0. But the binary instruction is e8 e1 fe ff ff. There is nothing that corresponds to 4003c0. What is that i am getting wrong?</p>
<p>Thanks. Bala</p>
