是！var与var！= NULL相同？(Is !var the same as var != NULL?)

 我想知道如果var是char *那么var和var != NULL是一样的。 
 
 这是一个非常小的POC，表明它不是一回事（或者我做错了什么？），但我不明白为什么。 
 
int main(void) {
    char *c = NULL;
    if(!c){
        printf("1\n");
    }else{
        printf("2\n");
    }

    if(c != NULL){
        printf("1\n");
    }else{
        printf("2\n");
    }
    return 0;
}
 
 输出是 
 
1
2
 
 我在x64 Arch Linux，GCC 4.8.2上运行这个 
 
 编辑：要么我需要一些真正的睡眠，或者你们都误解了程序的实际输出！ 请阅读几次。 
 
 !c意思是“如果c不是NULL”，它是假的，所以它应该在第一个if打印2 ，但它打印1 ！ 
 
 编辑：的确，我需要睡一会儿。 我不知道我在想什么。 谢谢你们！ 

I'm wondering if !var is the same as var != NULL if var is char *.
 
Here goes a really small POC that shows that it's not the same thing (or am I doing something wrong?) but I don't understand why. 
 
int main(void) {
    char *c = NULL;
    if(!c){
        printf("1\n");
    }else{
        printf("2\n");
    }

    if(c != NULL){
        printf("1\n");
    }else{
        printf("2\n");
    }
    return 0;
}
 
The output is
 
1
2
 
I'm running this on a x64 Arch Linux, GCC 4.8.2
 
EDIT: Either I need some real sleep or you all are misreading the actual output of the program! Please read it a few times.
 
!c means "if c is not NULL", which is false, so it should print 2 in the first if, but it prints 1!
 
EDIT: Indeed, I need to get some sleep. I don't know what was I thinking about. Thank you all!

原文：https://stackoverflow.com/questions/19646557