[C language] General method of expression evaluation

How expressions are evaluated:

• The expression is evaluated to see if there is a shaping promotion or arithmetic conversion, and then the calculation is performed
• When the expression is actually calculated, first look at the priority of the adjacent operators to decide who is calculated first
• In the case of the same priority of adjacent operators, the calculation order is determined by the associativity of the operators
    Of course, bad input methods will cause the program to have multipleAs a result, we should therefore write the calculation formula without an uprising.For example, the following code has different results in different compilation environments:

#include int main(){int i = 1;int ret = (++i)+(++i)+(++i);printf("ret = %d\n", ret);return 0;}

Different compilation environments can get the following results:

1. 10
2. 12
3. 9
   Therefore, we must pay attention to develop a good code input method.