字符串文字和指针之间有什么区别?

通常,可以使用任何字符串文本初始化指针,如 char *str = "Hello" . 我想这意味着 "Hello" 返回的地址 'H' . 但是,以下内容是不允许的。

#include <stdio.h>
#include <stdlib.h>

typedef struct {
    char name[64];
} Student;

Student initialization(char *str) {
    //Student tmp = {}; strcpy(tmp.name, str) //(*1)This is allowed.
    //Student tmp = {"Hello"}; //(*2)This is allowed.
    Student tmp = {str}; //(*3)This is not allowed.
    return tmp;
}

int main(void) {
    (...)
}

谁能告诉我为什么(*2)是允许的,但(*3)是不允许的?编译此代码会产生以下错误。

warning: initialization makes integer from pointer without a cast [-Wint-conversion]
     Student tmp = {str};
                    ^