“错误:分配给具有数组类型错误的表达式"当我分配一个结构字段(C) [英] "error: assignment to expression with array type error" when I assign a struct field (C)

问题描述

我是C语言的初学者，昨天我了解了C结构的使用以及这些结构在解决特定问题方面的可能应用.但是，当我尝试使用C IDE(代码块16.01)来学习C编程的这一方面时，遇到了一个奇怪的问题.代码如下:

I'm a beginner C programmer, yesterday I learned the use of C structs and the possible application of these ones about the resolution of specific problems. However when I was experimenting with my C IDE (Codeblocks 16.01) in order to learn this aspect of C programming, I've encountered a strange issue. The code is the following:

#include <stdio.h>

#define N 30

typedef struct{
     char name[N];
     char surname[N];
     int age;
} data;

int main() {
     data s1;
     s1.name="Paolo";
     s1.surname = "Rossi";
     s1.age = 19;
     getchar();
     return 0;
}

在编译期间，编译器(Windows下为GCC 4.9.3-1)向我报告了一条错误消息

During the compilation, the compiler (GCC 4.9.3-1 under Windows) reported me an error that says

错误:分配给具有数组类型错误的表达式"

"error: assignment to expression with array type error"

根据说明

s1.name="Paolo" 
s1.surname="Rossi" 

如果我愿意的话

data s1 = {"Paolo", "Rossi", 19};

有效. 我究竟做错了什么?

it works. What am I doing wrong?

推荐答案

您面临的问题

 s1.name="Paolo";

因为在LHS中，您使用的是 array 类型，该类型不是可分配的.

because, in the LHS, you're using an array type, which is not assignable.

要详细说明，请参见C11第6.5.16章

To elaborate, from C11, chapter §6.5.16

赋值运算符的左值应为可修改的左值.

assignment operator shall have a modifiable lvalue as its left operand.

，关于可修改的左值，请参见第6.3.2.1章

and, regarding the modifiable lvalue, from chapter §6.3.2.1

可修改的左值是一个 没有数组类型，[...]

A modifiable lvalue is an lvalue that does not have array type, [...]

您需要使用strcpy()来复制到阵列中.

也就是说，data s1 = {"Paolo", "Rossi", 19};可以正常工作，因为这不是直接涉及赋值运算符的赋值.在这里，我们使用了一个括起来的初始化程序列表，以提供 object 的初始值.遵循第6.7.9章中所述的初始化定律

That said, data s1 = {"Paolo", "Rossi", 19}; works fine, because this is not a direct assignment involving assignment operator. There we're using a brace-enclosed initializer list to provide the initial values of the object. That follows the law of initialization, as mentioned in chapter §6.7.9

每个用大括号括起来的初始化器列表都有一个关联的当前对象.当没有 存在指定，当前对象的子对象按以下顺序初始化 到当前对象的类型:下标顺序递增的数组元素，结构 成员按声明顺序排列，并且是联盟的第一个命名成员.[....]

Each brace-enclosed initializer list has an associated current object. When no designations are present, subobjects of the current object are initialized in order according to the type of the current object: array elements in increasing subscript order, structure members in declaration order, and the first named member of a union.[....]

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