Pitfalls of a question mark colon expression in C + +

Pitfalls of a question mark colon expression in C + +

Self-handling Baidu space

in doing a project, encountering strange bugs, the problem is similar to the following

int a=1,b=2,c=3,d;

D=a*b + c? 1:0;

Q What is the result of d?

design, I think the result should be 3 (1*2+1)

The actual D result is 1

because the question mark is lower in the precedence of the colon expression (the ternary operator precedence is less than the two-ary operator, such as the plus +)

so the actual run-time D and the following expressions are equivalent:

D= (a*b + c)? 1:0;

Instead of the a*b we expected (c? 1:0)

2014-12-11

Pitfalls of a question mark colon expression in C + +