Thread: Changed Program, Now Getting Syntax Errors

You have double &-signs. You're trying to get the address of an address..

And to clarify, strtof()'s second parameter is supposed to be the address of a pointer that you wish to fill in with the pointer to where in the string the input was stopped (e.g. if you have "123.45 234.56", the pointer would point at the space in the middle. You can use this for two things:
1. Determine if the entire string was accepted (the pointer will then point to a NUL character).
2. If you have multiple floats in a single string, the endPtr will indicate where the last field ended, so you can easily move on to the next field (in the case of space, it will be ignored in the beginning of the number, so it would just be case of passing the endPtr as input to strtof() to read the 234.56 next).

It can also be NULL, if you don't care about where the input ended.

--
Mats

Originally Posted by DonFord81

Each float occupies its own line, so what value can I assign to the second pointer so that it just moves to the next line naturally?

Well, assuming you use fgets() or some such that reads a line at a time, then you can't use that method. If that's the case, and you do not wish to check that the input was fully processes, I suggest you pass NULL as the second argument. And use a loop like you do to work your way through the data.

Code:

          fscanf(dataFile, "%s", stringArray[i]);
          if (stringArray[i][0] == EOF){
             break;
             }

This is wrong - stringArray[i][0] does not get set to EOF (it can not be, since it's a char, and EOF is an integer value). The return value from fscanf() will be set to EOF if the file ended (or some other error prevents reading the data).

--
Mats

Further to the previous post: I don't really see the point in reading each line into a big array, and then translating each entry to a float. Why not just read one line, and translate it to float then and there.

--
Mats

Originally Posted by DonFord81

I need to make sure each line is, in fact, a float before I convert it, don't I?

Yes, you would still need to check if it is a floating point number or not - but you don't need to read ALL lines FIRST, then convert them later on - just check the string, then convert it, as part of the reading process - there is no need to have an array 1000 strings stored, when you only need one string at a time to convert the content - unless I've missed something in what your program does.

--
Mats

So, something more along the lines of this:

Code:

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

int main(int argc, char *argv[]){
    FILE* dataFile;
    FILE* outputFile; 
    char string[80];
    float floatArray[1000];
    int i = 0;
    int number_of_lines;
    int number_of_floats;
    float sum_of_floats;
    float average;
    
    dataFile = fopen(argv[1], "rb");
    if (dataFile == NULL){
       fputs("File error", stderr);
       exit(1);
       }

    while (1){
          fgets(string, 80, dataFile);
          if (!isalpha(string[0])){
             floatArray[i] = strtof(&string[0], NULL);
             i++;
             }
          }          
    fclose(dataFile);
    number_of_floats = (i+1);

    for (i=0; i<number_of_floats; i++){
        sum_of_floats += floatArray[i];
        }
    
    average = ((sum_of_floats)/((float)(number_of_floats));
    
    printf("%f", average);
    
    fclose(dataFile);
    getch();
    return 0;
}

?

...

And now it's giving me a system error and shutting down prematurely.

Code:

&string[0]

is the same as

Code:

string

in this case.

Put the fgets() in the while-loop so that you end the loop when you hit the end of the file - I suspect your program crashes because you are using more than 1000 entries of the float array, becuase it keeps repeating the last actual line of the file, and crashing when it runs over the end of the array.

--
Mats