Check for error in scanf()

if i have a scanf for example:

scanf("%d",&x);

this is set to scan in a int data type to varabila x.

say the user inputs 2.5, i know the 2.5 will be trunkated to 2 but how useing a if statememt coukd i check if an int has been inputed.

hope the question makes sense...

thanks in advance....

I don't see why you want to do this. If your program is supposed to take an integer and the user enters a float value, that value is truncated into an integer and the input is correct.
If you want a float and the user enters an integer, once again the value is made to be the type you wanted and the input is correct.

To answer your question, I don't think you can do that, but if I think of something I'll be sure to let you know.

-Prelude

You cant, the scanf will stop reading numbers when it hits the '.' so your input will always be integer, you can't test for a float you dont read.
My advice is don't use scanf at all, especially with number inputs as it will leave the newlines in the input buffer, use fgets instead.

Code:

---

char temp[10], *temp_ptr;

temp_ptr = temp;

printf("\nEnter number ");
fgets(temp, 10, stdin);

while(*temp_ptr != '\n')
{
    /* move along string checking for a '.' which would mean the user entered a float */
}

---

Not great, but you see what I mean.

would i be correct in saying that the scanf function returns a value of 0 if the correct input has been entered and a value of 1 if incorrect input has been entered??

and if so how would i check for this returned value?

scanf returns the number of succesful conversions it has made, so if you want to read 2 letters scanf will return 2 if succesful.

Code:

---

printf("Enter 2 letters ");
if(scanf("%c%c", &a, &b) != 2)
    printf("Error");

---

I still say don't use scanf though

I agree, scanf is easy but error prone both in how you code it and in how it functions. In my opinion that makes it doubly bad. fgets is a little more involved, but your code will be better because of it.

Though I'd be lying if I said I didn't use scanf sometimes when I was lazy or going for compact code. :D

p.s. Thanks C_Coder, until now I had no idea what scanf returned, just that it did in fact return a value.

-Prelude