#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    int k;
    float a,b,c,x1,x2,tmp;
    a = -90.555;
    b = abs(a);
    c = fabs(a);
    k = int(a);

    std::cout <<"a, abs(a), k, abs(k)="<<
    a << ", "<< b << ", "<< c << ", " << k<<", "<<abs(k)<<   std::endl;
     return(0);
}




**********************************
出力は

a, abs(a), k, abs(k)=-90.555, 90.555, 90.555, -90, 90

となるはず。