Question

我参加了c项方案:

int bags[5]={20,5,20,3,20};
int main()
{
    int pos=5,*next();
    *next()=pos;   //problem with this line(should give error :lvalue required)
    printf("%d %d %d",pos,*next(),bags[0]);
    return 0; 
}
int *next()
{
    int i;
    for(i=0;i<5;i++)
        if(bags[i]==20)
            return (bags+i); 
    printf("error");
    exit(0);
}

the output to the program is 5 20 5 though i expected it to be lvalue required. can anyone tell the reason???

Answer 1

虽然 is not l Value,*next(>) is, this is an int, addressed by the sale Value if *next(<>(在bags' 阵列中注明)。

换言之,虽然你可以确定一项职能的回报价值,但你可以确定收益价值所处理的价值。

Answer 2

next() is not an lvalue, because function return values are not.
*next() is an lvalue, because its a value contained at some known memory address. Whether this address was obtained as a function s return value or otherwise (e.g. it was stored in a variable), doesn t matter.

Answer 3

参考操作员<代码>*_is a l Value。

“普通* 运营商表示间接。 [......]如果它指明了物体,其结果就是标注的值。 C99 6.3/4

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