Trouble Reading Data from Files

I have a file with numbers that I need for calculations and want to open the file, read the data and put the data in specific variables. The file has non-zero values, but my program just outputs zeros . . . please help!

The text file will look like this:
Params
1
2
3
4
5
6,7
Data
1,1
2,2
3,2
4,4
5,6

Code:

---

//Lunar Lander Phase 2

#include <stdio.h>

int main()

{
//        Declare variables

float G, vi, v, B, tstep, duration[100000], burnrate[100000], m, temp1, temp2, j;
int mi, ve, D, S, i = 0;


FILE *inFile;

inFile = fopen("LAND2.txt", "r");       
if (inFile == NULL)
{
printf("\nFailed to open the file.\n");                       
exit (1);
}

else
{
printf("\nThe file LAND2.txt was opened successfully.\n");
fscanf (inFile, "Params \n");                               
fscanf (inFile, "%f", &G);                               
fscanf (inFile, "%f\n", &vi);                       
fscanf (inFile, "%f\n", &B);                       
fscanf (inFile, "%f\n", &tstep);                       
fscanf (inFile, "%d\n", &mi);                               
fscanf (inFile, "%d\n", &ve);                       
fscanf (inFile, "%d,", &D);                       
fscanf (inFile, "%d", &S);                       
fscanf (inFile, "Data \n"); 

for ( i =0; i <= D; i++)
{
fscanf(inFile, "%d,%d\n", &temp1, &temp2);                                               
duration[i]=temp1;
printf("%d\n", duration[i]);
               
burnrate[i]=temp2;
printf("%d\n", burnrate[i]);
}
fclose (inFile);                               
}

return 0;
}

---

I'd suggest using fgets() to read each line into a buffer and then read on that buffer, you can then use sscanf and check the return code to verify each line was well formed and read in successfully. sscanf returns the number of items successfully read in.

I'd do something more like this in the else clause.

Code:

---

      if ( fscanf (inFile, "Params %f %f %f %f %d %d,%d Data",
                  &G, &vi, &B, &tstep, &mi, &ve, &D, &S) == 7 )
      {
        for ( i = 0; i < D; ++i )
        {
            if ( fscanf(inFile, "%f,%f\n", &duration[i], &burnrate[i]) == 2 )
            {
              printf("%g %g\n", duration[i], burnrate[i]);
            }
        }
      }

---

This might be a little ghetto, but it could work

Code:

---

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

#define MAXLINE 10

int main(void)

{

    char buff[MAXLINE];

    char temp1[] = "Params\n";
    char temp2[] = "Data\n";

    FILE *inFile;

    inFile = fopen("LAND2.txt", "r");     
    if (inFile != NULL)
    {
        while (fgets(buff, sizeof(buff), inFile) != NULL)
            if(strncmp(buff,temp1,sizeof(buff)) == 0)
                /*store data */

        rewind(inFile);

        while (fgets(buff, sizeof(buff), inFile) != NULL)
            if(strncmp(buff,temp2,sizeof(buff)) == 0)
                /*store data */


    }

/*probably should check for more errors*/ 

        fclose (inFile);                               
   

    return 0;
}

---

Quote:

---

Originally Posted by cwr

I'd suggest using fgets() to read each line into a buffer and then read on that buffer, you can then use sscanf and check the return code to verify each line was well formed and read in successfully. sscanf returns the number of items successfully read in.

---

Or I could wait for Dave to beat me to the punch.

Hey, I tried this and it didn't was successful . .. but didn't give me the array, and said that the if(fscanf) bit had "too many arguments for format"

Any suggestions?

Quote:

---

Originally Posted by Dave_Sinkula

I'd do something more like this in the else clause.

Code:

---

      if ( fscanf (inFile, "Params %f %f %f %f %d %d,%d Data",
                  &G, &vi, &B, &tstep, &mi, &ve, &D, &S) == 7 )
      {
        for ( i = 0; i < D; ++i )
        {
            if ( fscanf(inFile, "%f,%f\n", &duration[i], &burnrate[i]) == 2 )
            {
              printf("%g %g\n", duration[i], burnrate[i]);
            }
        }
      }

---

---

Quote:

---

Originally Posted by CConfusion

Hey, I tried this and it didn't was successful . .. but didn't give me the array, and said that the if(fscanf) bit had "too many arguments for format"

Any suggestions?

---

Yeah, get rid of the 8th S parameter. (I thought about editing that the other day, but tried to let it slip. Perhaps it is me that is slipping.)

Okay, I made the data read it in and I get the parameters for the first bit, but with the loop for the duration[i] and burnrate[i] arrays my program doesn't output the right stuff .. . this is what i've got currently.

And thanks for the help!

Code:

---

int main()

{
        //        Declare variables

                float G, vi, v, B, tstep, duration[100000], burnrate[100000], m, temp1, temp2, h = 500, total = 0, a, j;
                int mi, ve, D, S, i;


                FILE *inFile;
                FILE *outFile;                                                                                                                        //Declare a file outFile

                inFile = fopen("LAND2.txt", "r");                                                                //        Open file LAND2.txt to read

                if (inFile == NULL)
                {
                        printf("\nFailed to open the file.\n");                                        //        If the file doesn't exist print out can't open file and exit.
                        exit (1);
                }

//        Read in values for Params and Data

                else
                {
                                printf("\nThe file LAND2.txt was opened successfully.\n\n");

                          fscanf (inFile, "Params\n");                                                                // Read the Params line (on the first line)

                                fscanf (inFile, "%f\n", &G);                                                                //        Read the first parameter, gravitational acceleration (on the next line)
                                fscanf (inFile, "%f\n", &vi);                                                                // Read the second parameter,initial downward velocity (on the next line)
                                fscanf (inFile, "%f\n", &B);                                                                // Read the third parameter, initial burn rate (on the next line)
                                fscanf (inFile, "%f\n", &tstep);                                                        // Read the fourth parameter, time step (on the next line)
                                fscanf (inFile, "%d\n", &mi);                                                                // Read the fifth parameter, initial fuel mass (on the next line)
                                fscanf (inFile, "%d\n", &ve);                                                                // Read the sixth parameter, fuel exhaust speed (on the next line)
                                fscanf (inFile, "%d,%d\n", &D,&S);                                                        // Read the Data and Solutions values
                               
                                printf ("%f\n%f\n%f\n%f\n%d\n%d\n%d,%d\n", G, vi, B, tstep, mi, ve, D, S);
                               
                                fscanf (inFile, "Data\n");                                                          // Read the Data line

                for ( i = 0; i < D; i++ )
        {
                                fscanf(inFile, "%f,%f\n", &temp1, &temp2);                                //        Read in burnrate andduration til EOF
                               
                                temp1=duration[i];
                                printf("%f\n", duration[i]);
                               
                                temp2=burnrate[i];
                                printf("%f\n", burnrate[i]);               
                        }

                        fclose (inFile);                                                                                                                //        Close the file
                }

---

This is what I was messing with.

Code:

---

//Lunar Lander Phase 2
#include <stdio.h>

float duration[100000], burnrate[100000];

int main()
{
  static const char filename[] = "LAND2.txt";
  FILE *file = fopen(filename, "r"); 
  if ( file != NULL )
  {
      float G, vi, B, tstep;
      int mi, ve, D, i;

      printf("The file %s was opened successfully.\n", filename);
      if ( fscanf(file, "Params %f %f %f %f %d %d,%d Data",
                  &G, &vi, &B, &tstep, &mi, &ve, &D) == 7 )
      {
        for ( i = 0; i < D; ++i )
        {
            if ( fscanf(file, "%f,%f\n", &duration[i], &burnrate[i]) == 2 )
            {
              printf("%g %g\n", duration[i], burnrate[i]);
            }
        }
      }
      fclose(file);         
  }
  else
  {
      perror(filename);
  }
  return 0;
}

/* my output
The file LAND2.txt was opened successfully.
1 1
2 2
3 2
4 4
5 6
*/

---

Okay, I think my problem is that the file I'm reading will not always have 1,1 as it's starting values .. . so when you use fscanf ( .. . ....) ==2, it wont work for mine . . . (if I'm understanding what that line means correctly)

LAND2.txt

Code:

---

Params
10
20
30
40
50
60,5
Data
10,10
20,20
30,20
40,40
50,60

---

My output

Code:

---

The file LAND2.txt was opened successfully.
10 10
20 20
30 20
40 40
50 60

---

Okay, I got it thanks. My next (and hopefully last) problem is my file doesn't give me actual numbers when I run the last bit. This is what I have: (the problem is somewhere after the "outFile" bit.

Code:

---

//Lunar Lander Phase 2

#include <stdio.h>

//Declare function prototypes
float masschange(float duration, float burnrate, float total);

int main()

{
        //        Declare variables

                float G, vi, B, tstep, duration[100000], burnrate[100000], h = 500, total = 0, a, j;
                int mi, ve, D, S, i;


                FILE *inFile;                                                                                                                        //Declare a file outFile
                FILE *outFile;

                inFile = fopen("LAND2.txt", "r");                                                                //        Open file LAND2.txt to read

                if (inFile == NULL)
                {
                        printf("\nFailed to open the file.\n");                                        //        If the file doesn't exist print out can't open file and exit.
                        exit (1);
                }

//        Read in values for Params and Data

                else
                {
                        if ( fscanf (inFile, "Params\n %f\n %f\n %f\n %f\n %d\n %d\n %d,%d\n Data\n", &G, &vi, &B, &tstep, &mi, &ve, &D, &S) == 8)
              {
                for ( i = 0; i < D; ++i )
                {
                    if ( fscanf(inFile, "%f,%f\n", &duration[i], &burnrate[i]) == 2 )
                    {
                      printf("%2g %2g\n", duration[i], burnrate[i]);                                //Check the arrays to make sure the data was read correctly
                    }
                }
              }
                       
                        fclose(inFile);
                }


        outFile = fopen("LAND2Soln.txt", "w");                                                                //Make a file named LAND2Soln.txt to write to

        for (i = 0; i <= D; ++i)                                                                                                //Counting up by one for duration/burnrate values
        {
                float m, v;                                                                                                                                //        Find t for h = 0.0, set as td
                m = masschange(duration[i], burnrate[i], total);
       
                if (outFile == NULL)
                {
                        printf("Unable to open file.\n");                                                                //If the file doesn't exist end.
                        return 1;
                }
               
                else                                                                                                        //As long as the file exists, write the calculated velocity to it.
                {
                        for (j = 0; j <= duration[i]; j = j + tstep)                                //j keeps track of the amount of time each duration has run for
                        {
                      a = (((m*G) - (burnrate[i]*ve))/m);
                                v = v + (a*j);
                                           
                      printf("%f\n", v);
                                fprintf(outFile, "%f\n", v);                                                                                        //calculates the nth velocity

                                h = h - (v*j);

                                if (h <= 0)                                                                                                        //Stops when h = 0.
                                {
                                        return 1;
                                }
                  }
                }

        }

        fclose(outFile);

        return 0;
}

//        Define Custum Functions:


float masschange(float duration, float burnrate, float total)
{
        float mass = burnrate*duration;                        //        From Data array (needs a loop that goes through duration, and jumps burnrate after duration is up . . .
        total = total + mass;
        return total;
}

---