73 lines
1.4 KiB
C
73 lines
1.4 KiB
C
/* This file is part of the sample code and exercises
|
|
* used by the class "Advanced Programming in the UNIX
|
|
* Environment" taught by Jan Schaumann
|
|
* <jschauma@netmeister.org> at Stevens Institute of
|
|
* Technology.
|
|
*
|
|
* This file is in the public domain.
|
|
*
|
|
* You don't have to, but if you feel like
|
|
* acknowledging where you got this code, you may
|
|
* reference me by name, email address, or point
|
|
* people to the course website:
|
|
* https://stevens.netmeister.org/631/
|
|
*/
|
|
|
|
/* Use this program to illustrate how the
|
|
* call stack works by inspecting the various
|
|
* registers using gdb(1).
|
|
*
|
|
* Also inspect the return values of the
|
|
* differrent functions and how the behavior
|
|
* changes when you exit versus return
|
|
* from main.
|
|
*
|
|
* Note that you have to compile without
|
|
* warnings since we don't (explicitly)
|
|
* return in 'sum2'.
|
|
*
|
|
* cc -g sum.c
|
|
* gdb a.out
|
|
* display $rbp
|
|
* display $rsp
|
|
* display $rip
|
|
* display $rax
|
|
* break __start
|
|
* break main
|
|
* break sum
|
|
* break sum2
|
|
* run
|
|
*
|
|
* Also use this example to illustrate that
|
|
* you can manipulate both variables and
|
|
* registers while the program is running.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
int
|
|
sum1(int a, int b) {
|
|
int sum;
|
|
sum = a + b;
|
|
return sum;
|
|
}
|
|
|
|
int
|
|
sum2(int a, int b) {
|
|
int sum = a + b;
|
|
printf("sum2: %d\n", sum);
|
|
}
|
|
|
|
int
|
|
main() {
|
|
int a = 1;
|
|
int b = 2;
|
|
|
|
a += b;
|
|
printf("sum1 returned: %d\n", sum1(a, b));
|
|
printf("sum2 returned: %d\n", sum2(b, a));
|
|
return(0);
|
|
//exit(0);
|
|
}
|