##### 实例 - 计算两点距离(默认米,保留两位小数) ~~~ $j1 = 118.572436; $w1 = 24.908439; $j2 = 118.57237269; $w2 = 24.90872451; $obj = $T_D -> count($j1,$w1,$j2,$w2); ~~~ ##### 实例 - 计算两点距离(定义单位为公里,保留两位小数) ~~~ $j1 = 118.572436; $w1 = 24.908439; $j2 = 118.57237269; $w2 = 24.90872451; $obj = $T_D -> count($j1,$w1,$j2,$w2,2); ~~~ ##### 实例 - 计算两点距离(定义单位为公里,定义保留3为小数) ~~~ $j1 = 118.572436; $w1 = 24.908439; $j2 = 118.57237269; $w2 = 24.90872451; $obj = $T_D -> count($j1,$w1,$j2,$w2,2,3); ~~~