Why does my fscanf keep skipping random numbers?

Question

Basically I need to scan all the values from this file...which it pretty much does, but it seems to skip random ones so it ends up not lining up properly. (This is only part of what I need to do for the assignment so you are not "giving away the answer" and I still want to figure it out on my own, just need a little help figuring this one out, because I'm pretty stuck)

https://www.dropbox.com/sh/wterbuyxm76wwrz/AADEtolX68OFrKELI_lxT8_Ra/assignments%20and%20labs/labs/lab5_inputFile.txt?dl=0

Here is the code:

int main()
{
    FILE *fp;
    char x[15];
    float ID [1000];
    int i=0, j=0;
    float homework [1000];
    float lab [1000];
    float midterm [1000];
    float Final [1000];
    int count=0;
    char headers[35];
    char y;

    fp= fopen("lab5_inputFile.txt", "r");

    while (fscanf(fp, "%s", x)!=EOF){
        if (count > 728){
            fscanf(fp, "%f", &ID[i]);
            printf("ID : %.1f\n", ID[i]);
            fscanf(fp, "%f", &homework[i]);
            printf("Homework: %.1f\n", homework[i]);
            fscanf(fp, "%f", &lab[i]);
            printf("lab: %.1f\n", lab[i]);
            fscanf(fp, "%f", &midterm[i]);
            printf("Midterm: %.1f\n", midterm[i]);
            fscanf(fp, "%f", &Final[i]);
            printf("Final: %.1f\n", Final[i]);

            i++;
        }
            count ++;

    }
    printf("count = %d\n", count);
    fclose(fp);

I only scanned the last few values to make it easier to read/debug, in the actual code I will only be skipping the headings, there's also a lot of other things I plan to change before submitting this, like I might use pointer type and malloc instead of arrays and a bunch of other things, but my main question is how to fix the problem I am having with reading from the file into the arrays.

Thanks in advance!

Answer 1

You are skipping the first line x everytime. You should rewrite it as:

char x[100];
/* while (fscanf(fp, "%s", x)!=EOF){ */
fgets(x, 100, fp);  /* Skip first line */
for(; /* ever */; ) {
    if(5 == fscanf(fp, "%f%f%f%f%f", &ID[i], &homework[i], &lab[i], &midterm[i], &Final[i])) {
       printf("ID : %.1f\n", ID[i]);
       printf("Homework: %.1f\n", homework[i]);
       printf("lab: %.1f\n", lab[i]);
       printf("Midterm: %.1f\n", midterm[i]);
       printf("Final: %.1f\n", Final[i]);
       i++;
    } else break;
}

Live example here

Answer 2

OP's approach repeated reads "a group of non-white-space text and then 5 numbers". Code should read a line once, toss it and then repeated read groups of 5 numbers.

Read and toss first line, then read lines until EOF using fgets(). Scan the buffer with sscanf() or strtod().

char buf[100];
fgets(buf, sizeof buf, fp);  // Read and toss first line
i = 0;

while (fgets(buf, sizeof buf, fp) != NULL) {  // Read until EOF
  if ((i >= 1000) || (sscanf(buf, "%f%f%f%f%f", &ID[i], &homework[i], &lab[i], 
      &midterm[i], &Final[i]) != 5)) {
    fputs("Quit as too many lines or ill formatted\n", stderr);
    break;
  }
  printf("ID : %.1f\n", ID[i]);
  printf("Homework: %.1f\n", homework[i]);
  printf("lab: %.1f\n", lab[i]);
  printf("Midterm: %.1f\n", midterm[i]);
  printf("Final: %.1f\n", Final[i]);
  i++;
}

Answer 3

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

struct grade
{
    float ID;
    float homework;
    float lab;
    float midterm;
    float final;
};

#define ARRAYSIZE (1000)

int main()
{
    FILE *fp;
    struct grade studentGrades[ARRAYSIZE] = {{0},{0},{0},{0},{0}};
    int i=0;
    int count=0;


    if( NULL == (fp= fopen("lab5_inputFile.txt", "r") ) )
    {
        perror( "fopen for read of lab5_inputFile.txt" );
        exit(1);
    }

    // implied else fopen successful

    char* dummy = malloc(1000*sizeof(char) );
    if( NULL == dummy )
    {
        perror( "malloc for dummy buffer" );
        exit(2);
    }

    // implied else, malloc successful

    char * firstLine = fgets( dummy, sizeof(dummy), fp ); // step past first line of file
    if( NULL == firstLine )
    {
        perror( "fget of first line of file" );
        exit(3);
    }

    // implied else, fgets successful

    free( dummy );

    int itemCount = 0;
    for ( i = 0; i < ARRAYSIZE; i++ )
    {
        itemCount = fscanf(fp, " %f", &studentGrades[i].ID);
        if( EOF == itemCount ) // Note:making assumption that every line, 
                               // after first, is properly formatted
        {
            break; // exit for loop
        }
        if( 1 != itemCount )
        {
            perror("fscanf");
            exit(4);
        }

        // implied else read of ID successful, not end of file

        printf("ID : %.1f\n", studentGrades[i].ID);

        if( 1 != fscanf(fp, " %f", &studentGrades[i].homework) )
        {
            perror( "fscanf of homework");
            exit(5);
        }

        // implied else, read of homework successful

        printf("Homework: %.1f\n", studentGrades[i].homework);

        if( 1 != fscanf(fp, " %f", &studentGrades[i].lab) )
        {
            perror( "fscanf of lab" );
            exit(6);
        }

        // implied else, read of lab successful

        printf("lab: %.1f\n", studentGrades[i].lab);

        if( 1 != fscanf(fp, " %f", &studentGrades[i].midterm) )
        {
            perror( "fscanf of midterm" );
            exit(7);
        }

        // implied else, read of midterm successful

        printf("Midterm: %.1f\n", studentGrades[i].midterm);

        if( 1 != fscanf(fp, " %f", &studentGrades[i].final) )
        {
            perror( "fscanf of final" );
            exit(8);
        }

        // implied else, read of final successful

        printf("Final: %.1f\n", studentGrades[i].final);

        count ++;

    } // end for

    printf("count = %d\n", count);
    fclose(fp);

    return(0);
}