User pressing int or char....

[ingenting]

Hi all!

Well im kinda noobish at the c-programming language, not a full blown reatard tho. Lets say that i wanna write a simple program that wants to calculate the value of x in function:

y = kx + m

We want the user to enter the value of y, k and m and doing this by:

float y, k, m;

printf("Enter value for K: ");
scanf("%f", &k);

(i just stop here, dont need to write more code)

Here is my problem....... when i run the program and the user types the a char instead of an int my program crasch. How can i prevent this? Is there any test for keypress or something else i can do?

Ty.

[zacs7]

> (i just stop here, dont need to write more code)
If it crashes you do.

Check the return result of scanf().

[Salem]

Normally, I would suggest you separate input from conversion. It's not that the simple approach is hard, but it can be very tricky to make robust.

char buff[BUFSIZ];
if ( fgets( buff, BUFSIZ, stdin ) ) {
  if ( sscanf( buff, "%f", &k ) == 1 ) {
    // success, do stuff with k
  } else {
    // some error message
  }
}

Even sscanf has problems, in that the numeric conversions do not detect numeric overflow, and the string conversions are tricky to get right to prevent buffer overflow.

[ingenting]

Salem my man, tyvm for ya help!!!!

Now the program works as it should. One question tho...... about the size of buff[] in ya code.

If i want to use a macro as size for an array[] i usual do it like this:

#define SIZE 25

and then i can use it as index/size with me array like:

char arr[SIZE];

But i dont see any #define BUFSIZ, how come?

Again tyvm for help!!!

[Elysia]

BUFSIZ is usually a pre-defined macro somewhere, but it is not like it was not defined but rather that Salem left it out to simplify the code.

[ingenting]

OFC LOL sometimes me noobish glow just shines hehehe

ty for quick reply.