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From: KTrumpetsRule AT cs DOT com
Message-ID: <1ed.3702603c.2f5a12e3@cs.com>
Date: Fri, 4 Mar 2005 14:37:07 EST
Subject: problem with return
To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

I have a problem I'm having a really tough time tracking down.  Below is the
code.  out_xxxx.c calls function cyl_volume() which is in bm_xxxx.c.  As I go
along, I'm checking all the results against a Texas Instruments TI-30Xa
calculator.

THIS IS IN OUT_XXXX.C
/*
    locate(5,5);
    printf("Computing CYLINDER VOLUME ... ");
*/
    temp = 0.0;
    temp = cyl_volume(&eng_0);
    locate(5,5);
    printf("ptr_sim_0->V_1_ci = %10.6f, temp = %10.6f",
        ptr_sim_0->V_1_ci, temp);
    locate(13,5);
    ptr_sim_0->V_1_ci = cyl_volume(&eng_0);         /*  this is in bm_xxxx.c    
*/
    locate(13,5);
    printf("CYLINDER VOLUME - %10.6f cubic inches", ptr_sim_0->V_1_ci);
    pause(0);

THIS IS IN BM_XXXX.C
float cyl_volume(ENGINE *ptr_eng_0)
{
    float cyl_vol = 0.0;
    float temp1 = 0.0, temp2 = 0.0, temp3 = 0.0;

    cyl_vol = PI * (pow(ptr_eng_0->bore/2, 2)) *
                ptr_eng_0->stroke;

/* start debug */
    locate(7,5);
    printf("inside cyl_volume()");
    locate(8,5);
    printf("ptr_eng_0->bore = %10.6f, ptr_eng_0->stroke = %10.6f",
        ptr_eng_0->bore, ptr_eng_0->stroke);
    locate(9,5);
    printf("ptr_eng_0->bore/2 = %10.6f, pow(ptr_eng_0->bore/2, 2) = %10.6f",
        ptr_eng_0->bore/2, pow(ptr_eng_0->bore/2, 2));
    locate(10,5);
    printf("PI = %10.10f, cyl_vol = %10.6f", PI, cyl_vol);
    locate(11,5);
    temp1 = pow(ptr_eng_0->bore/2, 2);
    temp2 = temp1 * ptr_eng_0->stroke;
    temp3 = temp2 * PI;
    printf("temp1 = %10.6f, temp2 = %10.6f, temp3 = %10.6f", temp1, temp2, 
temp3);
    return temp3;
/* end debug */

    /* return cyl_vol; */
}

THIS IS RESULTS ON SCREEN
  ptr_sim_0->V_1_ci =   0.000000, temp = 1102290688.000000

  inside cyl_volume())
  ptr_eng_0->bore =   2.975000, ptr_eng_0->stroke =   3.230000
  ptr_eng_0->bore/2 =   1.487500, pow(ptr_eng_0->bore/2, 2) =   2.212656
  PI = 3.1415927000, cyl_vol =  22.452583
  temp1 =   2.212656, temp2 =   7.146879, temp3 =  22.452583

  CYLINDER VOLUME - 1102290688.000000 cubic inches

As you can see from the section titles "THIS IS RESULTS ON SCREEN" even though
temp3 contains the correct value, it doesn't seem to be returned as such.  All
assigned values and computed values check out OK within the cyl_volume()
function.  Again, this is shown by the "RESULTS" screen.

Any help would be appreciated.


Bill

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