#include <stdio.h>
#include <stdlib.h>
#define EPSINON 1e-3
#define ABS(a) (((a)>0)?(a):(-a)) //？：不支持表达式嵌套
#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("输入三条边的值：");
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("等边三角形。");
else if(equal(max_square, tmp))
puts("等腰直角三角形。");
else if(max_square < tmp)
puts("等腰锐角三角形。");
else
puts("等腰钝角三角形。");
}
else
{
if(equal(min, mid))
puts("等边三角形。");
else
puts("等腰锐角三角形。");
}
}
else if(equal(max_square, tmp))
puts("直角三角形。");
else if(max_square < tmp)
puts("锐角三角形。");
else
puts("钝角三角形。");
}
}
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("输入错误，a b c必须大于零，是否新输入(y/n)：");
}
else if(judge_err_flag)
{
judge_err_flag = 0;
while((cs=getchar())!='\n' && (cs=getchar())!=EOF);
printf("组不成三角形,是否重新输入(y/n)：");
}
else
{
while((cs=getchar())!='\n' && (cs=getchar())!=EOF);
printf("是否再输入一组数据(y/n)：");
}
ch = getchar();
}
while(ch=='y' || ch=='Y' || ch=='\n');
puts("Goodbye!");
return 0;
}
