Turbo C compiler issue, sqrt() function not working with variable arguments

Question

I searched the question similar to my problem Similar problem. But my problem is when using Turbo C compiler v3.0. Should I have to do some additional work for math.h file? please help.

int main (void){
    double result, a;
    clrscr();
    printf("Enter a # for square root.\n");
    scanf("%f",&a);
    printf("a = %f\n",a);
    result = sqrt(a);
    printf("a = %f  and square root is %f\n",a, result);
    getch();
    return 0;
    }

The Output is like this:

Enter a # for square root.

64

a = 0.000000

a = 0.000000 and square root is 0.000000

Answer 1

For scanf(), %f is for float. You need to use %lf for double:

printf("Enter a # for square root.\n");
scanf("%lf",&a);

This is in contrast to printf() where type-promotion allows %f to be used for both float and double.