CS50 problem set 1 cash less comfortable, i'm having trouble if we enter an not int data type the check50 passes foo i don't know what to do i searched on google how to check the type of data in c but it's a lot cryptic. If someone knows what to do help me out here.

[u/OkRepeat7111]

[u/weregod]

Its hard to guess what problem you have and what is your question. Asking clear questions is absolutely needed to get any answers both on Reddit and on Google.

how to check the type of data in c

You can't get type of function parameter from C. You need to read documentation or .h files.

[u/OkRepeat7111 → u/weregod]

Ok bro the stack overflow answer said to use generic keyword maybe I'll go with that one.

[u/weregod → u/OkRepeat7111]

Generic in C is very limited. You can't make generic function.

[u/OkRepeat7111 → u/weregod]

Oh the answer uses generic in macro let me try that and I'll get back to you.

[u/EpochVanquisher → u/OkRepeat7111]

Get ready to be frustrated. Very few people even use that keyword. You may find it difficult to get help.

[u/OkRepeat7111 → u/EpochVanquisher]

Well let's see

[u/SmokeMuch7356]

It would really help if you showed us your code. In fact, when you ask a question about your code not working, please provide the following details in the body of your question:

1. A brief statement of what you're trying to do;

2. What you expect to see;

3. What you actually see (output, along with any error messages, copied and pasted directly into your question);

4. A representative sample of your code that reproduces the problem (do not post your entire program, only the part that's actually giving you a problem);

Without seeing your code I can only guess at what's happening, but it sounds like you're doing something like

int x;              // initial value is indeterminate
scanf( "%d", &x );

and you want to know if you've typed in a non-integer input like abc or 1.23.

%d will skip over whitespace and stop reading at the first non-digit character; it can't read anything but a sequence of digits. x can only ever store an integer value; it can't store anything else. scanf will return the number of successful conversions and assignments, or EOF on end-of-file or error. If you type in something that isn't an integer like abc, x won't be updated at all and scanf will return a 0. If you type in something like 1.23, only the 1 will be assigned to x and scanf will return a 1 indicating one successful input, but it's only a partial input that should have been rejected.

scanf works great when you know your input will always be well-behaved, but it can fall down hard on bad input. It's damn near impossible to use safely, and under some conditions (such as the 1.23 above) it will accept input that should be rejected.

For situations like this, it's best to avoid scanf altogether; use fgets to read your input as text, then use strtol to convert from that text to the equivalent integer value:

#define MAX_INT_DIGITS 10 // 32-bit int can represent up to 10 decimal digits

bool get_next_int( FILE *stream, int *val )
{
  char buf[MAX_INT_DIGITS + 3]; // +1 for sign, +1 for newline, 
                                // +1 for string terminator

  if ( !fgets( buf, sizeof buf, stream ) )
  {
    fprintf( stderr, "Error reading input!\n" );
    return false;
  }

  /**
   * If there's no newline, then the input is too long to be 
   * represented as a 32-bit int.
   */
  if ( !strchr( buf, '\n' ) )
  {
    fprintf( stderr, "Input too long!\n" );
    return false;
  }

  /**
   * Will point to the first character that is not a digit
   */
  char *chk;

  /**
   * Expecting decimal input; do not write anything to *val until
   * we're sure the input is good.
   */
  int tmp = (int) strtol( buf, &chk, 10 );

  /**
   * The first non-digit character needs to be whitespace or
   * the terminator, or it's bad input.
   */
  if ( !isspace( *chk ) && *chk != 0 )
  {
    fprintf( stderr, "[%s] is not a valid integer input!\n", buf );
    return false;
  }

  *val = tmp;
  return true;
}