[英]Struct initialization behaviour in arrays C
我在文件test.c中有以下简单代码:
#include <stdio.h>
#include <string.h>
struct Student {
char name[10];
int grade;
};
int main(){
struct Student s = {.name = "Joe", .grade = 10}; //correct
struct Student students[10];
students[0] = {.name = "John", .grade = 10}; //error
students[1] = s; //correct
struct Student some_other_students[] = {
{.name = "John", .grade = 10}
}; //correct
students[2].grade = 8;
strcpy(students[2].name, "Billy"); //correct?!? O_o
return 0;
}
编译后出现此错误
test.c|14|error: expected expression before '{' token|
数组在students[0] = {.name = "John", .grade = 10};
是否应该正确初始化students[0] = {.name = "John", .grade = 10};
?。 以这种方式进行初始化时: struct Student s = {.name = "Joe", .grade = 10};
然后将其设置为像students[1] = s;
这样的数组students[1] = s;
我没有错误。 只是一个假设,但可能是{.name = "Joe", .grade = 10}
表达式在内存中没有引用,并且结构数组仅仅是对已初始化结构的引用数组?
但是如果数组只是初始化结构的引用,那又如何工作呢? students[2].grade = 8;
?
您只能在定义变量时对其进行初始化。 定义变量后,在分配给变量时不能使用与初始化相同的语法。 您尝试分配给数组元素没有关系,重要的是您使用分配而不是初始化。
话虽如此,即使语法有点笨拙(IMO),也有一种解决方法,那就是使用复合文字创建一个临时的伪结构对象,并将其复制到变量中:
students[0] = (struct Student){.name = "John", .grade = 10};
以上相当于
{
// Define and initialize a "temporary" Student structure object
struct Student temp = {.name = "John", .grade = 10};
// Assign it to students[0]
students[0] = temp;
}
或者,您可以在定义数组时初始化它:
struct Student students[10] = {
{.name = "John", .grade = 10}
};
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