Order of evaluation of expression

Question

I\'ve just read that order of evaluation and precedence of operators are different but related concepts in C++. But I\'m still unclear how those are different but related?.<

Answer 1

Consider the below example:

#include 
#include 
int main(void)
{
    double a = 1 + UINT_MAX + 1.0;
    double b = 1 + 1.0 + UINT_MAX;
    printf("a=%g\n", a);
    printf("b=%g\n", b);
    return 0;
}

Here in terms of math as we know it, a and b are to be computed equally and must have the same result. But is that true in the C(++) world? See the program's output.