Exploring printf function Behavior

The C compiler does not have uniform regulations on some behaviors, and programmers cannot pray that the compiler will always understand the program according to your ideas. Therefore, when writing high-quality code, if you have doubts, it is best to use another safe way.

During programming, a printf ("% d", a, a ++) Statement is run. The initial value of variable A is 2, this statement prints 3 and 2, which makes me puzzled for a long time.

Later, through experiments, I understood how GCC works (other compilers do not have to go deep into it, but the style of writing code needs to be refined)

Printf scans from right to left, and then outputs from left to right! The process can be understood as follows:
Printf ("% d/n % d", a, a ++ );
From right to left: A ++ // push
2, A + 1
A // Push 3
Output: POP 3 // print 3
Pop
2 // print 2

 

Later, I wrote a program experiment again:

# Include <stdio. h> <br/> int fun1 () <br/>{< br/> printf ("fun1/N"); <br/> return 1; <br/>}< br/> int fun2 () <br/>{< br/> printf ("fun2/N"); <br/> return 2; <br/>}< br/> void main () <br/>{< br/> int A = 2; <br/> printf ("% d/N", ++ a, a); <br/> printf ("% d/N ", fun1 (), fun2 (); <br/>}

 

Conclusion: this problem does not need to be further investigated, but in order to avoid another error, you must temper your encoding style.