是否有任何C函数可以求值标准库中定义的字符串表达式? [英] Is there any C function that can evalute a string expression defined in the standard library?
问题描述
我正在寻找一个可以将字符串表达式评估为整数的函数，例如f.e.:
10/2 + 4 * 3-(12 + 5);//等于0 插入值为 0 的 int 类型的对象.
具有复杂功能的功能将是可取的，即使这并不需要小时:
2 ^(1/2)-99 在标准C库(如果已编译，则为C89，C90)中是否定义了这样的定义?
是否有具有这种功能的非标准库?
表达式支持的字符越多.
但是即使是+，-，*，/，()之类的基本操作也可以.
在标准C库中是否定义了这样的定义(如果已编译，则为C89，C90)?
否，甚至在最新的C11或C18标准库中也没有.
是否有具有这种功能的非标准库?
我也找不到一个.您必须编写自己的函数才能完成此任务.
也许扫描字符串，然后在第一步中将其中的每个值存储到单独的字符串中.
正如我在评论中已经建议的那样， 算术运算符也应存储在单独的字符串中，但稍后由自制例程进行评估. 但是可以在此处找到很好的示例和建议，在该示例中，已经向用户询问了类似(如果不相同)的问题: I am looking for a function that can evaluate a string expression into an integer, like f.e.: into an object of type A function for complex operation would be preferable even though that's not the need of the hour:
Is there any such definition defined in the standard C library (C89, C90, if it's compiled)? Is there any non-standard library which has such an function? The more the characters the expression supports the better it is. But even basic operation like +,-,*,/,() would do. Is there any such definition defined in the standard C library (C89, C90, if it's compiled)? No, not even in the more recent standard libraries of C11 or C18. Is there any non-standard library which has such an function? I couldn´t found one either. You have to write your own function to accomplish that. Maybe scan the string and store every value in it to a separate string at the first step. As I already suggested in the comments, The arithmetic operators shall be stored in separate strings also, but later evaluated by a self-made routine. But good examples and recommendations can be found here, where a user have been asked a similar (if not the same) question: C: convert a mathematical expression string into an int with the result 这篇关于是否有任何C函数可以求值标准库中定义的字符串表达式?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！ strtol 用于将字符串中的 11 之类的整数值转换为 int .您可能需要利用它.库中还有一个 atoi 函数，用于将字符串中的整数值转换为 int ，但是此函数更容易出错，因此不应该使用./p>10/2+4*3-(12+5); //Equals 0
int with the value of 0.2^(1/2)-99
strtol is used to convert an integer value like 11 in a string to a value of type int. You might need to take use of that. In the libraries there is also a function of atoi to convert an integer value inside a string to an int but this function is more susceptible for errors and should not be used.
