C 语言实例2—— 输入三角形三边长度，判断是什么类型三角形（等边、等腰、不能构成三角形）

#include <stdlib.h>
#include <stdio.h>
int main()
{
float a;
float b;
float c;
float temp;
/*
** Prompt for and read the data.
*/
printf( "Enter the lengths of the three sides of the triangle: " );
scanf( "%f %f %f", &a, &b, &c );
/*
** Rearrange the values so that a is the longest and c is the shortest.
*/
if( a < b )
{
 temp = a;
 a = b;
 b = temp;
}
if( a < c )
{
 temp = a;
 a = c;
 c = temp;
}
if( b < c )
{
 temp = b;
 b = c;
 c = temp;
}
/*
** Now see what kind of triangle it is. Note that if any of the sides
** is <= 0 (and we really only have to check the shortest one for this),
** or if the two shorter sides together are shorter than the longest
** side, it isn’t a triangle at all.
*/
if( c <= 0 || b + c < a )
printf( "Not a triangle.\n" );
else if( a == b && b == c )
 printf( "Equilateral.\n" );
else if( a == b || b == c )
printf( "Isosceles.\n" );
else
printf( "Scalene.\n" );
return EXIT_SUCCESS;
}