[英]C struct problem
I am trying to learn about structs in C, but i do not understand why i cannot assign the title as i my example: 我试图在C中学习结构,但我不明白为什么我不能像我的例子那样分配标题:
#include <stdio.h>
struct book_information {
char title[100];
int year;
int page_count;
}my_library;
main()
{
my_library.title = "Book Title"; // Problem is here, but why?
my_library.year = 2005;
my_library.page_count = 944;
printf("\nTitle: %s\nYear: %d\nPage count: %d\n", my_library.title, my_library.year, my_library.page_count);
return 0;
}
Error message: 错误信息:
books.c: In function ‘main’:
books.c:13: error: incompatible types when assigning to type ‘char[100]’ from type ‘char *’
LHS is an array, RHS is a pointer. LHS是一个数组,RHS是一个指针。 You need to use
strcpy
to put the pointed-to bytes into the array. 您需要使用
strcpy
将指向的字节放入数组中。
strcpy(my_library.title, "Book Title");
Take care that you do not copy source data > 99 bytes long here as you need space for a string-terminating null ('\\0') character. 请注意,此处不要复制> 99字节长的源数据,因为您需要空格来终止字符串终止的空('\\ 0')字符。
The compiler was trying to tell you what was wrong in some detail: 编译器试图在某些细节上告诉你错误:
error: incompatible types when assigning to type 'char[100]' from type 'char *'
错误:从类型'char *'分配类型'char [100]'时出现不兼容的类型
Look at your original code again and see if this makes more sense now. 再看看你的原始代码,看看现在是否更有意义。
As the message says, the issue is you are trying to assign incompatible types: char*
and char[100]
. 正如消息所述,问题是您正在尝试分配不兼容的类型:
char*
和char[100]
。 You need to use a function like strncpy
to copy the data between the 2 您需要使用类似
strncpy
的函数来复制2之间的数据
strncpy(my_library.title, "Book Title", sizeof(my_library.title));
title
是一个字符数组 - 这些不能在C中赋值。使用strcpy(3)
。
char* and char[100] are different types. char *和char [100]是不同的类型。
You want to copy those char elements inside the .title buffer. 您想要在.title缓冲区中复制这些char元素。
strncpy(my_library.title, "Book Title", sizeof(my_library.title));
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