Programming Forums > Application Development > C

Fall Back Son · Oct 31st, 2006, 9:09 PM

this is my new code. to give u an idea of whether ive been trying or not, the old code was ten times this long

#include <stdio.h>
int main ()

{
float miles;
float gallons;
float counter;
float lowest;
float highest;
float mpg;

lowest = 100;
highest = 0;
counter = 0;
scanf("%f", &miles);

while ( miles > -.5 )
{
scanf("%f", &gallons);

(miles/gallons) = mpg;
if (mpg < lowest) 
{
lowest = mpg;
}

(miles/gallons) = mpg;
if (mpg > highest)
{
highest = mpg;
}

counter = counter + 1;

scanf("%f", &miles);

/* the above calculates number of trips */
}

return (0);

}

Fall Back Son · Oct 31st, 2006, 9:28 PM

sweet. i figured out what was wrong. miles/gallons = pg doesnt work, it assigns a value to something that IS already a value. it has to be mpg = miles/gallons

Prm753 · Oct 31st, 2006, 9:31 PM

Quote:

Originally Posted by Fall Back Son

sweet. i figured out what was wrong. miles/gallons = pg doesnt work, it assigns a value to something that IS already a value. it has to be mpg = miles/gallons

Yeah, Dev-C++ threw an "invalid lvalue" compiler error.

You might want to use indentation. You can also use counter++; instead of counter = counter + 1;. I am curious to know why your program only accepts values under -.5?

Fall Back Son · Oct 31st, 2006, 9:45 PM

no, it only accepts values OVER -.5

at the end of the data file used as my input, there is "-1", which serves to stop the while loops from running. . since it is a MPG analysis program, obviously all normal values will be positive. so the while loop will run until the end of the program, at which point the value "-1" will cause it to stop

im estatic right now, it finally works. although I still havent figured out how to get the average of all the MPGs... but I'll figure it out.

DaWei · Oct 31st, 2006, 9:53 PM

The code:

(Toggle Plain Text)

#include <stdio.h>

int ohGoodGosh (char *troubleInRiverCity)
{
    fprintf (stderr, "%s\n", troubleInRiverCity);
    return -1;
}

int main ()
{
    FILE *trips;
    char tripFile [] = "trips.txt";
    double totMiles = 0.0;
    double totGallons = 0.0;
    double thisTrip;
    double thisConsumption;
    int numTrips = 0;
    int status;

    trips = fopen (tripFile, "r");
    if (!trips) return ohGoodGosh ("Couldn't open file");

    puts ("Trips:\n");
    while (1)
    {
        status = fscanf (trips, "%lf %lf\n", &thisTrip, &thisConsumption);
        if (status != 2)
        {
            /*
            Failed to get complete record.
            */
            if (feof (trips)) break; /* But that's okay, end of file */
            /*
            Two parts not found, or read error
            */
            return ohGoodGosh ("Error reading file");
        }
        /*
        Display this record
        */
        printf ("%.2lf miles, %.2lf gallons\n", thisTrip, thisConsumption);
        /*
        Accumulate
        */
        totMiles += thisTrip;
        totGallons += thisConsumption;
        /*
        --------> Counter <--------
        */
        numTrips++;
    }
    /*
    Wrapup
    */
    puts ("\nThe final skinny:\n");
    printf ("%.2lf miles total, %.2lf gallons total for %.2lf average mpg\n\n", totMiles, totGallons, totMiles/totGallons);

    return 0;

}

The good file:

Quote:

100 10.75
250 40
300 35.4
275 25
108 13

The bad file:

Quote:

100 10.75
250 a
300 35.4
275 25
108 13

The good file output:

Quote:

Trips:

100.00 miles, 10.75 gallons
250.00 miles, 40.00 gallons
300.00 miles, 35.40 gallons
275.00 miles, 25.00 gallons
108.00 miles, 13.00 gallons

The final skinny:

1033.00 miles total, 124.15 gallons total for 8.32 average mpg

The bad file output:

Quote:

Trips:

100.00 miles, 10.75 gallons
Error reading file

The nonexistent file output:

Quote:

Couldn't open file

Fall Back Son · Oct 31st, 2006, 10:06 PM

umm... what does that mean? ^^ (i dont know what you are trying to tell me.)

anyway, i have a question, and it is:
why doesn't the "if" loop (condition is (20 <= trips <= 30)) correctly calculate the number of trips that were between 20-30 MPG? it compiles correctly, just doesnt get the correct answer.

edit: nevermind, another stupid error. the condition was wrong... it has to be mpg in the condition, not trips. also, i need && ... what I had in the condition is mathematically true, but not for C .

(Toggle Plain Text)

#include <stdio.h>
int main ()

{
float miles;
float gallons;
float counter;
float lowest;
float highest;
float mpg;
float trips;

trips = 0;
lowest = 100;
highest = 0;
counter = 0;

scanf("%f", &miles);

while ( miles > -.5 )
{

scanf("%f", &gallons);

mpg = (miles/gallons);

if ( mpg < lowest ) 
{

lowest = mpg;

}

mpg = (miles/gallons);

if (mpg > highest)
{
highest = mpg;
}

if ( 20 <= trips <= 30 )
{
trips = trips + 1 ;
}

counter = counter + 1;

scanf("%f", &miles);

/* the above calculates number of trips */
}

printf("Package truck MPG analysis :\n");
printf("%.3f trips were taken \n", counter);
printf("The best was %.3f MPG \n", highest);
printf("The worst was %.3f MPG \n", lowest);
printf("The number of trips between 20-30 MPG was %f \n", trips);

return (0);

}

Fall Back Son · Nov 1st, 2006, 1:14 PM

If anyone is interested, here is the final code. thanks for all the help, everything was appreciated! Btw andro, the reason I couldn't do what you were telling me to do was because I didn't understand what you were saying. It makes sense to me now that I figured out the answer... but it was way over my head beforehand.

(Toggle Plain Text)

#include <stdio.h>
int main ()

/* File: proj5.c
**Author: Kyle Moser
**Date: Tuesday, October 31
**My web ID: 5727
**Section: 
**email: kmo1@umbc.edu
**description: This program calculates the number of trips delivery trucks 
took, as well as the highest MPG of any of those trips, the lowest MPG of 
any of those trips, the average MPG, and the number of trips between 20-30 
MPG. ***/


{
float miles;
float gallons;
float counter;
float lowest;
float highest;
float mpg;
float trips;
float average;

average = 0;
trips = 0;
lowest = 100;
highest = 0;
counter = 0;

scanf("%f", &miles);

/* Get number of trips */

while ( miles > -.5 )
{

scanf("%f", &gallons);

mpg = (miles/gallons);

/* get lowest MPG */

if ( mpg < lowest ) 
{

lowest = mpg;

}

mpg = (miles/gallons);

/* get highest MPG */

if (mpg > highest)
{
highest = mpg;
}

/* get number of trips between 20 and 30 MPG */

if (mpg >= 20 && mpg <= 30 )
{
trips = trips + 1 ;
}

counter = counter + 1;

/* get total MPG */

if (mpg > 0)
{
average = (average + mpg) ;
}

scanf("%f", &miles);

}

/* Get average MPG */
average = ( average / counter );

printf("Package truck MPG analysis :\n");
printf("%.3f trips were taken \n", counter);
printf("The best was %.3f MPG \n", highest);
printf("The worst was %.3f MPG \n", lowest);
printf("The average was %.3f MPG \n", average);
printf("The number of trips between 20-30 MPG was %f \n", trips);

return (0);

}

DaWei · Nov 1st, 2006, 1:49 PM

Quote:

umm... what does that mean? ^^ (i dont know what you are trying to tell me.)

It's merely example code, including testing the read operations for success, which only noobs and schlocks fail to do. Try putting in 'x' when your program is looking for a number (some user surely will) and you'll see what I mean.

Incidentally, the tab key is right under your left pinky if you move said pinky a little up and to the left.

Oct 31st, 2006, 9:09 PM	#11
Fall Back Son Professional Programmer Join Date: Oct 2006 Posts: 311 Rep Power: 3	this is my new code. to give u an idea of whether ive been trying or not, the old code was ten times this long (Toggle Plain Text) #include <stdio.h> int main () { float miles; float gallons; float counter; float lowest; float highest; float mpg; lowest = 100; highest = 0; counter = 0; scanf("%f", &miles); while ( miles > -.5 ) { scanf("%f", &gallons); (miles/gallons) = mpg; if (mpg < lowest) { lowest = mpg; } (miles/gallons) = mpg; if (mpg > highest) { highest = mpg; } counter = counter + 1; scanf("%f", &miles); /* the above calculates number of trips / } return (0); } #include <stdio.h> int main () { float miles; float gallons; float counter; float lowest; float highest; float mpg; lowest = 100; highest = 0; counter = 0; scanf("%f", &miles); while ( miles > -.5 ) { scanf("%f", &gallons); (miles/gallons) = mpg; if (mpg < lowest) { lowest = mpg; } (miles/gallons) = mpg; if (mpg > highest) { highest = mpg; } counter = counter + 1; scanf("%f", &miles); / the above calculates number of trips */ } return (0); }

Oct 31st, 2006, 10:06 PM	#16
Fall Back Son Professional Programmer Join Date: Oct 2006 Posts: 311 Rep Power: 3	umm... what does that mean? ^^ (i dont know what you are trying to tell me.) anyway, i have a question, and it is: why doesn't the "if" loop (condition is (20 <= trips <= 30)) correctly calculate the number of trips that were between 20-30 MPG? it compiles correctly, just doesnt get the correct answer. edit: nevermind, another stupid error. the condition was wrong... it has to be mpg in the condition, not trips. also, i need && ... what I had in the condition is mathematically true, but not for C . (Toggle Plain Text) #include <stdio.h> int main () { float miles; float gallons; float counter; float lowest; float highest; float mpg; float trips; trips = 0; lowest = 100; highest = 0; counter = 0; scanf("%f", &miles); while ( miles > -.5 ) { scanf("%f", &gallons); mpg = (miles/gallons); if ( mpg < lowest ) { lowest = mpg; } mpg = (miles/gallons); if (mpg > highest) { highest = mpg; } if ( 20 <= trips <= 30 ) { trips = trips + 1 ; } counter = counter + 1; scanf("%f", &miles); /* the above calculates number of trips / } printf("Package truck MPG analysis :\n"); printf("%.3f trips were taken \n", counter); printf("The best was %.3f MPG \n", highest); printf("The worst was %.3f MPG \n", lowest); printf("The number of trips between 20-30 MPG was %f \n", trips); return (0); } #include <stdio.h> int main () { float miles; float gallons; float counter; float lowest; float highest; float mpg; float trips; trips = 0; lowest = 100; highest = 0; counter = 0; scanf("%f", &miles); while ( miles > -.5 ) { scanf("%f", &gallons); mpg = (miles/gallons); if ( mpg < lowest ) { lowest = mpg; } mpg = (miles/gallons); if (mpg > highest) { highest = mpg; } if ( 20 <= trips <= 30 ) { trips = trips + 1 ; } counter = counter + 1; scanf("%f", &miles); / the above calculates number of trips */ } printf("Package truck MPG analysis :\n"); printf("%.3f trips were taken \n", counter); printf("The best was %.3f MPG \n", highest); printf("The worst was %.3f MPG \n", lowest); printf("The number of trips between 20-30 MPG was %f \n", trips); return (0); }

Nov 1st, 2006, 1:14 PM	#17
Fall Back Son Professional Programmer Join Date: Oct 2006 Posts: 311 Rep Power: 3	If anyone is interested, here is the final code. thanks for all the help, everything was appreciated! Btw andro, the reason I couldn't do what you were telling me to do was because I didn't understand what you were saying. It makes sense to me now that I figured out the answer... but it was way over my head beforehand. (Toggle Plain Text) #include <stdio.h> int main () /* File: proj5.c Author: Kyle Moser Date: Tuesday, October 31 My web ID: 5727 Section: email: kmo1@umbc.edu description: This program calculates the number of trips delivery trucks took, as well as the highest MPG of any of those trips, the lowest MPG of any of those trips, the average MPG, and the number of trips between 20-30 MPG. **/ { float miles; float gallons; float counter; float lowest; float highest; float mpg; float trips; float average; average = 0; trips = 0; lowest = 100; highest = 0; counter = 0; scanf("%f", &miles); / Get number of trips / while ( miles > -.5 ) { scanf("%f", &gallons); mpg = (miles/gallons); / get lowest MPG / if ( mpg < lowest ) { lowest = mpg; } mpg = (miles/gallons); / get highest MPG / if (mpg > highest) { highest = mpg; } / get number of trips between 20 and 30 MPG / if (mpg >= 20 && mpg <= 30 ) { trips = trips + 1 ; } counter = counter + 1; / get total MPG / if (mpg > 0) { average = (average + mpg) ; } scanf("%f", &miles); } / Get average MPG / average = ( average / counter ); printf("Package truck MPG analysis :\n"); printf("%.3f trips were taken \n", counter); printf("The best was %.3f MPG \n", highest); printf("The worst was %.3f MPG \n", lowest); printf("The average was %.3f MPG \n", average); printf("The number of trips between 20-30 MPG was %f \n", trips); return (0); } #include <stdio.h> int main () / File: proj5.c Author: Kyle Moser Date: Tuesday, October 31 My web ID: 5727 Section: email: kmo1@umbc.edu description: This program calculates the number of trips delivery trucks took, as well as the highest MPG of any of those trips, the lowest MPG of any of those trips, the average MPG, and the number of trips between 20-30 MPG. **/ { float miles; float gallons; float counter; float lowest; float highest; float mpg; float trips; float average; average = 0; trips = 0; lowest = 100; highest = 0; counter = 0; scanf("%f", &miles); / Get number of trips / while ( miles > -.5 ) { scanf("%f", &gallons); mpg = (miles/gallons); / get lowest MPG / if ( mpg < lowest ) { lowest = mpg; } mpg = (miles/gallons); / get highest MPG / if (mpg > highest) { highest = mpg; } / get number of trips between 20 and 30 MPG / if (mpg >= 20 && mpg <= 30 ) { trips = trips + 1 ; } counter = counter + 1; / get total MPG / if (mpg > 0) { average = (average + mpg) ; } scanf("%f", &miles); } / Get average MPG */ average = ( average / counter ); printf("Package truck MPG analysis :\n"); printf("%.3f trips were taken \n", counter); printf("The best was %.3f MPG \n", highest); printf("The worst was %.3f MPG \n", lowest); printf("The average was %.3f MPG \n", average); printf("The number of trips between 20-30 MPG was %f \n", trips); return (0); }

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Oct 31st, 2006, 9:28 PM	#12
Fall Back Son Professional Programmer Join Date: Oct 2006 Posts: 311 Rep Power: 3	sweet. i figured out what was wrong. miles/gallons = pg doesnt work, it assigns a value to something that IS already a value. it has to be mpg = miles/gallons

Oct 31st, 2006, 9:45 PM	#14
Fall Back Son Professional Programmer Join Date: Oct 2006 Posts: 311 Rep Power: 3	no, it only accepts values OVER -.5 at the end of the data file used as my input, there is "-1", which serves to stop the while loops from running. . since it is a MPG analysis program, obviously all normal values will be positive. so the while loop will run until the end of the program, at which point the value "-1" will cause it to stop im estatic right now, it finally works. although I still havent figured out how to get the average of all the MPGs... but I'll figure it out.

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Programming Forums > Application Development > C

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