有人可以解释一下这个while循环是什么意思吗？

Question

while (a = b) 
   ;

I know that it will probably not be anything so complex but I don't understand what it will become

Answer 1

Assuming that a and b are variables...

What this says is "Assign the value of b to a . If this value is non zero, do the inside of the loop (which is "do nothing"). Continue assigning until a (post assignment) is zero."

Theoretically, b could be changed throughout the program via an interrupt or other source. It could be mapped to an internal register, for example. Note that this is also changing a , which could set off a chain of events that makes b zero, ending the loop.

If b and a are not changing/are not volatile, this could serve (in a jankey way) as "clear a , assert that b is zero." If b is non-zero, the program will hang.

Most likely though, it's meant to be while (a == b); , which can be treated as "assert that a is not equal to b, and hang otherwise."

Answer 2

if b=0 then it will not execute. Otherwise, it will be an infinite loop. Here, the value of b assigned in a. Hope you got it.

Answer 3

void stringCAT(char *s1, char *s2)
{
    while(*s1 != '\0')
    {
        s1++;
    }

    for(; *s1 = *s2; s1++,s2++)
    {
        ;
    }
}

The for loop includes your answer. The middle of for statement is condition like inside a while() . This for loop runs until *s2= '\\0' and copies data from s2 to s1 at the same time. This is valid for the type of char.