An easy way to parse an expression?

Question

C++ / C#

Tell me the easiest way to parse expressions in C. Expressions like 26+35/16+81*67-12. There are no brackets, spaces, etc. An array of characters is passed to the function, you need to get double at the output.

double calculate( char str[] )
{
      //Суть вопроса
}

Answer 1

Explore:

• Marshalling yard algorithm
  
• Reverse Polish notation
  
• Calling a translator/compiler from your program
  

Answer 2

Type in Google "Algorithm shunting yard". Floor calculator of the 2nd year of study at the university;)