字符串计算公式，在编辑框输入你想要的计算公式，本程序，只提供几个简单的函数，只要是C支持的函数你可以在相应的控件函数里面添加！-string formula, the editorial input box you want the formula for calculating the process, only a few simple functions, as long as C is a function of your support in the corresponding con