结构体中的int字段未初始化什么值？ [英] What value have int fields in struct not initialized yet?

问题描述

在程式码中：
...

  #define MAXELEMNTS 100 
 
 struct book 
 {
 int number; 
 char name [31]; 
 char author [31]; 
 int year; 
 char publisher [31]; 
}; 
 
 struct book bkStruct [MAXELEMENTS]; 
  

...

字段（数字和年份）默认初始化为0时，其他的char字段初始化，但不是这两个？或者他们有神知道什么价值？在我的经验，他们有值= 0，但我不知道是这个一般规则，所以我必须确定！

没有部分初始化这样的东西。
如果通过为单个成员指定值来初始化结构，所有其他成员将自动初始化（适当种类的 0 ）。

  struct book 
 {
 int number; 
 char name [31]; 
 char author [31]; 
 int year; 
 char publisher [31]; 
}; 
 
 struct book book1; //没有初始化
 struct book book2 = {.author =pmg}; //初始化所有的book2 
 
 struct book bkStruct1 [MAXELEMENTS]; // uninitialized array 
 struct book bkStruct2 [MAXELEMENTS] = {0}; // initialized array 
 //（每个元素的每个成员）
  

_{：一些实现可能会抱怨丢失大括号上的完美合法的数组初始化。这是这些实现的问题。}

In the code: ...

 #define MAXELEMNTS 100

 struct book
 {
     int number;
     char name[31];
     char author[31];
     int year;
     char publisher[31];
 };

 struct book bkStruct[MAXELEMENTS];

...

Are the integer fields (number and year) initialized to 0 by default when the other char fields are initialized but not these two? Or do they have god-knows-what value? In my experience they do have value = 0, but I am not sure is this general rule so I must be sure!

Best regards, Papo

解决方案

In C there is no such thing as "partial initialization". If a struct is initialized by specifying a value for a single member, all the other members are automagically initialized (to 0 of the proper kind).

struct book
{
    int number;
    char name[31];
    char author[31];
    int year;
    char publisher[31];
};

struct book book1; // no initialization
struct book book2 = { .author = "pmg" }; // initialization of ALL of book2

struct book bkStruct1[MAXELEMENTS]; // uninitialized array
struct book bkStruct2[MAXELEMENTS] = {0}; // initialized array
                                          // (every member of every element)

_{Note: some implementations may complain about missing braces on the perfectly legal array initialization. That is a problem with those implementations.}

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