Could you tell me what is wrong?

Question

#include <stdio.h>
#include <math.h>

double a,b,c;
double d= b * b - 4 * a * c;

int main() {

printf("Enter a, b and c: ");
scanf("%lf %lf %lf", &a, &b, &c);
if (a == 0)
{
double x;
x = -c/b;
printf("x= %2f\n",x);
}
else if(d>0) {
double x1;
x1 -= -b + sqrt(d) / (2 * a);
double x2;
x2 = -b - sqrt(d) / (2 * a);

printf("x1=%lf\nx2=%lf", x1, x2);
}
else
printf("It won't work");

return 0;
}
At the moment it doesn't even compile. The output is:

/usr/bin/cmake --build /mnt/c/Users/radbi/CLionProjects/untitled4/cmake-build-debug --target untitled4 -- -j 4
[ 50%] Building C object CMakeFiles/untitled4.dir/main.c.o
/mnt/c/Users/radbi/CLionProjects/untitled4/main.c:5:15: error: initializer element is not constant
double d= b * b - 4 * a * c;
^
CMakeFiles/untitled4.dir/build.make:62: recipe for target 'CMakeFiles/untitled4.dir/main.c.o' failed
make[3]: *** [CMakeFiles/untitled4.dir/main.c.o] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/untitled4.dir/all' failed
make[2]: *** [CMakeFiles/untitled4.dir/all] Error 2
CMakeFiles/Makefile2:79: recipe for target 'CMakeFiles/untitled4.dir/rule' failed
make[1]: *** [CMakeFiles/untitled4.dir/rule] Error 2
Makefile:118: recipe for target 'untitled4' failed
make: *** [untitled4] Error 2

Answer 1

Hello. I'm not sure but I think the problem is that d=b*b-4*a*c but a, b, c haven't a value.

Answer 2

instead of defining the expression of d in global scope just define d in global scope then after Ur first scanf statement type d = " Ur expression "