Thread: Space separated input in C

I want to make a program that allows the use to input space separated numbers then read those numbers into an array. I wrote a program which works for all cases except when the user inputs data that is separated by more than 1 space or has multiple trailing spaces.

Sample input and output:

Code:

Input:"0 1 2 3 4 5 6 7 8 9"
Output: [0,1,2,3,4,5,6,7,8,9]

Input:"0 1 2     3   4    5  6        7   8       9        "
Output: [0,1,2,3,4,5,6,7,8,9]

Input:"0123456789"
Output: Error: Bad input format.

Input:"0 1 24 3 5 12 4 6"
Output: Error: Bad input format.

Input:"0 1 2.3 4 5 6,7"
Output: Error: Bad input format.

Input:"0 1 2 -3 4 -5 6 7"
Output: Error: Bad input format.

Input:"0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9"
Output: Error: Too many numbers.

Code:

    int input_array[10] = { 0 };
    int size = 0;
    int ch1 = 0, ch2 = 0;

    while (ch1 != '\n' && ch2 != '\n') {
        ch1 = getchar();
        if (ch1 == EOF || ch1 == '\n' || !isdigit(ch1)) {
            printf("Error: Bad input format.");
            exit(EXIT_FAILURE);
        }
        ch2 = getchar();
        if (ch2 != EOF && ch2 != '\n' && ch2 != ' ') {
            printf("Error: Bad input format.");
            exit(EXIT_FAILURE);
        } else {
            input_array[size] = ch1 - '0';
            size+=1;
        }
        if ((ch1 == '\n' || ch2 == '\n') && size != DICE_SIZE) {
            printf("Error: Too many numbers.");
            exit(EXIT_FAILURE);

        }
    }

The code above works for all cases except when the inputs are not separated by exactly 1 space with no trailing or leading spaces, so I get an error for the following input but

Code:

Input:"0 1 2     3   4    5  6        7   8       9        "
Output: Error: Bad input format.
Desired Output: [0,1,2,3,4,5,6,7,8,9]

I modified the code above and now it works for this input "0 1 2 3 4 5 6 7 8 9 " but it stopped working for "0123456789", i.e. I get:

Code:

Input:"0123456789"
Output: [0,1,2,3,4,5,6,7,8,9]
Desired Output: Error: Bad input format.

Your loop should read only one character per iteration.
Otherwise, you have too many combinations of characters to deal with.

Eg

Code:

while ( (ch1 = getchar()) != EOF ) {
  if ( ch1 == '\n' ) ...
  else if ( ch1 == ' ' ) ...
  else if ( isdigit(ch1) ) ...
  else if ....
  else ...
}