#include <stdio.h>
#include <stdlib.h>
#define EPSINON 1e-3
#define ABS(a) (((a)>0)?(a):(-a)) //? : nesting of expressions is not supported
#define ZERO(x) ((x)>-EPSINON && (x)<EPSINON)
#define MAX(a,b) (((a)>(b))?(a):(b))
#define MIN(a,b) (((a)<(b))?(a):(b))
float a, b, c;
float max, mid, min;
char input_err_flag = 0;
char judge_err_flag = 0;
int equal(float a, float b)
{
float tmp;
tmp = a - b;
tmp = ZERO(ABS(tmp));
return tmp;
}
void input(void)
{
a = b = c = 0;
printf(" Enter the values of three edges: ");
scanf("%f %f %f",&a, &b, &c);
if(!(a>0) || !(b>0) || !(c>0))
{
input_err_flag = 1;
}
}
void sort(void)
{
max = MAX(MAX(a,b),c);
min = MIN(MIN(a,b),c);
if(MAX(a,b) < c)
mid = MAX(a,b);
else
mid = MAX(MIN(a,b),c);
}
void judge(void)
{
float max_square, mid_square, min_square, tmp;
if(max >= (mid+min))
{
judge_err_flag = 1;
}
else
{
max_square = max * max;
mid_square = mid * mid;
min_square = min * min;
tmp = mid_square + min_square;
if(equal(mid,min) || equal(max, mid))
{
if(equal(mid, min))
{
if(mid == max)
puts(" Equilateral triangle. ");
else if(equal(max_square, tmp))
puts(" An isosceles right triangle. ");
else if(max_square < tmp)
puts(" An acute isosceles triangle. ");
else
puts(" Isosceles obtuse triangle. ");
}
else
{
if(equal(min, mid))
puts(" Equilateral triangle. ");
else
puts(" An acute isosceles triangle. ");
}
}
else if(equal(max_square, tmp))
puts(" Right triangle. ");
else if(max_square < tmp)
puts(" An acute triangle. ");
else
puts(" An obtuse triangle. ");
}
}
int main(void)
{
char cs, ch;
do
{
input();
sort();
judge();
if(input_err_flag)
{
input_err_flag = 0;
while((cs=getchar())!='n' && (cs=getchar())!=EOF);
printf(" Typing error, a b c Must be greater than zero, whether new input (y/n) : ");
}
else if(judge_err_flag)
{
judge_err_flag = 0;
while((cs=getchar())!='n' && (cs=getchar())!=EOF);
printf(" Unformed triangle , Whether or not to retype (y/n) : ");
}
else
{
while((cs=getchar())!='n' && (cs=getchar())!=EOF);
printf(" Whether to enter another set of data (y/n) : ");
}
ch = getchar();
}
while(ch=='y' || ch=='Y' || ch=='n');
puts("Goodbye!");
return 0;
}