How would I go about scanning float values in a text file with whitespace characters using I/O Redirection?

Question

I'm pretty new to programming in C and I have a school assignment that requires me to use I/O Redirection and strictly use scanf to read the data from a text file.

I'm mostly checking whether or not the code I've written makes sense and is a plausible method because I can't check whether it works currently (may or may not have dropped my laptop).

Here's what I've written so far.

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

int main(void){
    int readingsLen = 5040;
    float readings[readingsLen];
    float* readingsPtr = (float*)readings;

    while (scanf("%.2f", readingsPtr) != EOF){
        readingsPtr++;
    }
}

Additionally, here's what the text file looks like. Added the \n to show where the line ends.

 22.12  22.43  25.34  21.55 \n

Answer 1

You can use the pointer:

#include <stdio.h>
#define LEN 5040

int main(void){
    float readings[LEN];
    for(float *readingsPtr = readings; readingsPtr < readings + LEN; readingsPtr++) {
        switch(scanf("%f", readingsPtr)) {
            case EOF:
               return 0;
            case 0:
               printf("failed to read float\n");
               return 1;
            default:
               break;
         }
        printf("read %.2f\n", *readingsPtr);
    }
}

and here is resulting output:

read 22.12
read 22.43
read 25.34
read 21.55

I find this version, that uses an index instead of a pointer, easier to read:

#include <stdio.h>
#define LEN 5040

int main(void){
    float readings[LEN];
    for(size_t i = 0; i < LEN; i++) {
        switch(scanf("%f", readings+i)) {
            case EOF:
               return 0;
            case 0:
               printf("failed to read float\n");
               return 1;               
            default:
               break;
        }
        printf("read %.2f\n", readings[i]);
    }
}