Allow them to enter numbers only

Please help me
I want users to enter numbers only

Code:

---

#include <stdio.h>

int main () {
        float        num;

        printf        ("Please Enter Number You want Square of: ");
        scanf        ("%f", &num);       
        >>>Something here it tells users to enter numbers only if they enter alphabets then it should not work<<<<
        printf  ("%0.2f squared is equal to %0.2f\n", num, num * num);
       
        return 0;
}

---

You do want to read the user input as text, check if it is numeric, and then do the conversion.

it does work
lets say if it ask user to enter number, and if user enters K
than my program should tell them to enter numbers only

I would still read the input as text, and do checks and conversion myself.

But you might want to search the documentation for scanf to see, if there's some return values specified for it.

you can check the return value of scanf

Code:

---

double a;
if (scanf("%lf", &a) != 1) {
//the user didn't enter a number
} else {
...
}

---

But it will work if the user enters a number followed by something else. Eg, "10.5 asdf"

Depends on what you are trying to do, that can be good or bad.