How to read input from stdin until EOF read line by line with each line containing four space separated integers in C

How to read input from stdin until EOF read line by line with each line containing four space separated integers in C. It could be inputted by commands like this:

$ echo 1 2 3 4 | ./myProgram

or

$ cat file.txt

1 2 3 4

0 -3 2 -4

$ ./myProgram < file.txt

"This is where it would output my calculations"

Then I want to save the individual integers to int variables.

char strCoordinates[101];
    char *ptr;
    int coordinates[4];
    long int tempCoordinates;
    while(scanf("%s", strCoordinates) != EOF) {
        tempCoordinates = strtol(strCoordinates, &ptr, 10);
        int lastDigit = 0;
        for (int x = 4; x >= 4; x--) {
            lastDigit = tempCoordinates % 10;
            coordinates[x] = lastDigit;
            tempCoordinates = (tempCoordinates - lastDigit) / 10;
            }
    }

This is what I was trying but it seems way to complicated . . .

Any help would be greatly apprecated. Not sure whether to use scanf(), sscanf(), fscanf(), gets()