Tracing Programs
The Task
trace
The Program
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/**************************************************
* File: trace.c *
* Author: S. Bogar *
* Date: 2/2/96 *
* Section: 101 *
* EMail: bogar@cs.umbc.edu *
* *
* This program illustrates local variables and is *
* to be used to demonstrate the techniques of *
* tracing a program by hand. The non-meaningful *
* function and variable names are intentional, *
* since they are not REALLY doing anything that *
* is meaningful except teaching you to trace *
* function calls *
**************************************************/
#include <stdio.h>
int Foobar (int b);
int Geez (int c);
int main ()
{
int a = 1, b = 2, c = 3;
c = Geez (a);
b = Foobar(c);
printf("main: a = %d, b = %d, c = %d\n", a, b, c) ;
return 0;
}
/*********************************************
** Function: Foobar
** Usage: Foobar(b);
**
** Input: an arbitrary integer, b
** Output: returns b++
** outputs values of local vars, a common
** technique for debugging programs
*********************************************/
int Foobar (int b)
{
int a, c;
a = Geez (b);
c = b++;
printf("Foobar: a = %d, b = %d, c = %d\n",
a, b, c);
return (c);
}
/*********************************************
** Function: Geez
** Usage: Geez(c);
**
** Input: an arbitrary integer, c
** Output: returns c + 100
** outputs values of local vars, a common
** technique for debugging programs
*********************************************/
int Geez (int c)
{
int a, b;
a = c + 100;
b = 2 * a;
printf("Geez: a = %d, b = %d, c = %d\n", a, b, c);
return (a);
}
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The Sample Run
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Geez: a = 101, b = 202, c = 1
Geez: a = 201, b = 402, c = 101
Foobar: a = 201, b = 102, c = 101
main: a = 1, b = 101, c = 101
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