Thread: Calculating speed

Hello I'm working on a project for a school presentation, The program is not really finished but 1 module is causing a linker error , "LNK1120 Unresolved external" and I'm unable to find why.

Code:

void CalSpeed(CAR cars[] , int count)
{
    int i;
    float slopeRad;
    float slopeTangent;


    printf("MODEL\tSKIDLENGTH\tROADSLOAP\tSPEED\n");
    for(i = 0; i < count; i++)
    {
        slopeRad = cars[i].roadslope * pi / 180;
        slopeTangent = sin(slopeRad) / cos(slopeRad) ;
        Speed[i] = sqrt(30 * cars[i].skidlength * (slopeTangent + brakefactor));
        printf("%s\t%d\t%d\t%.2f\n", cars[i].carmodel , cars[i].skidlength , cars[i].roadslope , Speed[i]);
    }
}

Here is the prototype for the module

Code:

void CalSpeed(CAR cars[] , int count);

And its call is at the end of this function:

Code:

void readValues(){
    int x = 0;
    char correct[3];
    char test[50];


       while(!feof(stdin))
       {
          printf("Enter A cars information below Enter ctrl + Z to end entry\n\n");
          printf("\n\t\t===================================\n\n\t\t  ENTRY  WINDOW  \n\n\t\t===================================");
          fflush(stdin);
          printf("\nEnter car model=>");
          fgets(car[x].carmodel , 50 , stdin);
          if(feof(stdin))
              break;
          printf("\nEnter the skid length of car=>");
          fgets(test , 50 , stdin);
          check(test);
          car[x].skidlength = atoi(test);
          while (car[x].skidlength <= 0)
          {
             system("cls");
             allegro_message("INVALID. Enter  a skid length greater than 0");
             printf("Enter skid length => ");
             fgets(test , 50 , stdin);
             check(test);
             car[x].skidlength = atoi(test);
          }
          printf("\nEnter the degree of the road slope=>");
          fgets(test , 50 , stdin);
          check(test);
          car[x].roadslope = atoi(test);
          while (car[x].roadslope > 30 || car[x].roadslope < -30)
          {
             system("cls");
             fflush(stdin);
             allegro_message("INVALID. Enter a degree > -30 and < +30");
             printf("Enter roadsloap => ");
             fgets(test , 50 , stdin);
             check(test);
             car[x].roadslope = atoi(test);
          }
          system("cls");
          printf("Is this information correct? [Y] or [N]:\n\n");
          printf("%s: ", "Model");
          printf("%s\n" , car[x].carmodel);
          printf("%s: " , "Skidlength");
          printf("%d\n\n" , car[x].skidlength );
          printf("%s: " , "Roadslope");
          printf("%d\n\n" , car[x].roadslope );
          fgets(correct , 2 , stdin);
          correct[0] = toupper(correct[0]);
          response_check(correct);
          correct[0] == 'N' ? x-- : x++;
          system("cls");
       }
      CalSpeed(car , x -1);
}

If anyone could help it would be most appreciated

What's with all the complicated stdin stuff?

Get rid of feof > SourceForge.net: Feof - cpwiki
Get rid of fflush(stdin) > SourceForge.net: Fflush - cpwiki

Also, you have a ton of copy/pasting, especially when you're error checking.

I suppose I could come up with a better way of terminating the loop than feof and make the code a bit more readable but for now the code is still a work in progress I definitely plan on fixing it up a little bit once I have the main components running , the only problem I have at the moment tho is the linker error related to the function CalSpeed , If I remove the function the program runs , however when I have it I get a linker error.

Nope , the project is all in one source file , I can run it if I block out that one function.

Do you think its possible the problem may be in the way I used the functions sqrt , sin or cos?

Nevermind commenting them out I got the same error.

Code:

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include<string.h>
#include<math.h>




const float pi = 3.1416;
const float brakefactor = 0.7;
float Speed[];
FILE *record;
FILE *backup;


struct car_records
	{
		char carmodel[50];
		int skidlength;
		int roadslope;
	};
typedef  struct car_records CAR;


void CalSpeed(CAR cars[] , int count);


CAR car[100];








int main()
{
	char num[3];
	char answer[3];
	
	strcpy(car[0].carmodel , "Toyota");
	car[0].roadslope = 20;
	car[0].skidlength = 35;
	CalSpeed(car , 1);
	return 0;
}


	
	






void CalSpeed(CAR cars[] , int count)
{
	int i;
	float slopeRad;
	float slopeTangent;


	printf("MODEL\tSKIDLENGTH\tROADSLOAP\tSPEED\n");
	for(i = 0; i < count; i++)
	{
		slopeRad = cars[i].roadslope * pi / 180;
		slopeTangent = sin(slopeRad) / cos(slopeRad) ;
		Speed[i] = 0;//sqrt(30 * cars[i].skidlength * (slopeTangent + brakefactor));
		printf("%s\t%d\t%d\t%.2f\n", cars[i].carmodel , cars[i].skidlength , cars[i].roadslope , Speed[i]);
	}
}

Sorry about the delay , in theory this should run but I get the linker error.

I don't get a linker error, but you're not allocating any space for Speed.

Wow that was what was causing the problem I forgot to allocate space for Speed, I really didn't imagine that was causing it. Thanks For the help everyone