y =(int)sqrt((double)x)；

-

Scanf_s is more secure than scanf. Scanf _ s checks the type of input data to see if the input data matches the variable.

For example, the string char name[ 10], whether the given string is too long or not, and whether it exceeds the declared size. The name [10] can only contain 9 characters and 1 string terminators.

Scanf does not check the input data.