Thread: Problem with float and argv

I need to be able to read floats from a .DAT file. However, I do not want to assume that all of the lines will strictly be floats (comment lines, etc., are quite common in .DAT files that I use).

When I write the code to a file, the file contains the entire contents of my .DAT file correctly, but when I ask the program to display the contents of the array (buffer), it gives incorrect values. What am I doing wrong?

Here's the code:

Code:

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

int main(int argc, char *argv[]){
    FILE* dataFile;
    long file_size;
    float* buffer;
    size_t result;
    int i;
    
    dataFile = fopen (argv[1], "rb");
    if (dataFile==NULL){
       fputs ("File error", stderr);
       exit (1);
       }

    // obtain file size:
    fseek (dataFile, 0, SEEK_END);
    file_size = ftell (dataFile);
    rewind (dataFile);

    // allocate memory to contain the whole file:
    buffer = (float*) malloc (sizeof(float)*file_size);
    if (buffer == NULL){
       fputs ("Memory error", stderr);
       exit (2);
       }

    // copy the file into the buffer:
    result = fread (buffer, 1, file_size, dataFile);
    if (result != file_size){
       fputs ("Reading error", stderr);
       exit (3);
       }

    /* the whole file is now loaded in the memory buffer. */
    for (i=0; i<file_size; i++){
        printf("%f\n", buffer[i]);
        }
    getch();
    fclose (dataFile);
    free (buffer);
    return 0;
}

How would I go about fixing that, then?

Originally Posted by DonFord81

I need to be able to read floats from a .DAT file. However, I do not want to assume that all of the lines will strictly be floats (comment lines, etc., are quite common in .DAT files that I use).

When I write the code to a file, the file contains the entire contents of my .DAT file correctly, but when I ask the program to display the contents of the array (buffer), it gives incorrect values. What am I doing wrong?

In that case the file contents are really ASCII characters, besides the fread() is going to read a single item from the input file.