[英]passing struct to function C
I have initialised 3 instances of a cache I have defined using typedef. 我已经初始化了3个使用typedef定义的缓存实例。 I have done some processing on them in a serious of if statements in the following way :
我以下列方式对它们进行了一些认真的if语句处理:
cache cache1;
cache cache2;
cache cache3;
int a;
void main(...) {
if (a == 0) {
cache1.attribute = 5;
}
else if (a == 1) {
cache2.attribute = 1;
}
else if (a == 2) {
cache3.attribute = 2 ;
}
However now I need to make the design modular in the following way: 但是,现在我需要通过以下方式使设计模块化:
cache cache1; cache cache2; cache cache3; void cache_operator( cache user_cache, int a ) { user_cache.attribute = a; } void main(...) { if (a == 0) { cache_operator(cache1,5); } else if (a == 1) { cache_operator(cache2,1); } ...
I am having trouble with passing the cache to the method. 我在将缓存传递给方法时遇到麻烦。 I'm used to java programming and I'm not very familiar with c pointers.
我习惯了Java编程,对c指针不是很熟悉。 However, if I pass the cache itself as shown above I am passing a copy of the cache on the stack which then produces results different to the original code.
但是,如果如上所述传递高速缓存本身,则会在堆栈上传递高速缓存的副本,从而产生与原始代码不同的结果。 How do I properly transform the first design into the second design when it comes to passing the appropriate cache to the function and making sure it is accessed properly.
在将适当的缓存传递给函数并确保正确访问该函数时,如何将第一个设计正确转换为第二个设计。
In C language, if you want to keep track of the original 'data' instead of creating a copy in the function, you have to pass the pointer of that data to that function. 在C语言中,如果要跟踪原始“数据”而不是在函数中创建副本,则必须将该数据的指针传递给该函数。
Pointer in C is just like the reference to object in JAVA. C中的指针就像对JAVA中对象的引用一样。
Following is how you do it. 以下是您的操作方法。
void cache_operator( cache *user_cache, int a )
{
user_cache->attribute = a;
}
Following is how you call the function. 以下是如何调用该函数。
cache_operator(&cache1,5);
I also started with JAVA. 我也从JAVA开始。 I don't know why some universities nowadays use JAVA as beginning language... It is quite strange, since JAVA is a high-level language making the abstraction of low-level detail, whereas C is a rather low-level language.
我不知道为什么现在有些大学将JAVA用作开始语言...这很奇怪,因为JAVA是一种高级语言,抽象了低级细节,而C是一种相当低级的语言。 In the past, this will never be the case..
在过去,情况永远不会如此。
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