这是真的，有没有必要学习C，因为C ++中包含的一切吗？ [英] Is it true that there is no need to learn C because C++ contains everything?

问题描述

我正在一类C ++编程和教授告诉我们，没有必要学习C，因为C ++包含C以及面向对象的功能应有尽有。然而，也有人告诉我，这未必是真实的。任何人都可以阐明这一些轻？

解决方案

概述：

这几乎是事实，C ++是C的超集，和你的教授是在正确的没有必要单独学习C。

C ++增加整个面向对象的方面中，通用编程的方面，以及具有不那么严格的规则（如需要在各函数的顶部被声明变量）。 C ++的确改变了一些C方面，比如结构的定义，虽然仍然在一个超集的方式。

为什么它不是一个严格的超例子：

这个维基百科文章有这样的差异几个很好的例子：

  

一个经常遇到的区别是
  这C允许的隐式转换
  void *的其它指针类型，但是C ++
  才不是。因此，以下是有效的C
  code：

 为int * i = malloc的（sizeof的（INT）* 5）;
 

  
  

...但是，使其在C工作，
  C ++人会需要使用明确
  投：

 为int * I =（INT *）malloc的（的sizeof（int）的* 5）
 

  
  

另一种常见的便携性问题
  那C ++定义了许多新的关键字，
  如新的类，这可能是
  用作标识符（例如变量
  名称）在C程序中。

此Wikipedia文章有进一步的差异，以及：

  

C ++编译器禁止转到越过初始化，如下面的C99 code：

 无效FN（无效）
 {
  转到高炮;
  INT I = 1;
 弗莱克：
   ;
 }
 

你应该先了解？

您应该学习C ++第一，不是因为学习C首先会伤害你，不是因为你必须忘掉什么（你不会），但因为在第一次学习C没有任何好处。你会最终学会只是关于C反正一切，因为它是多还是少了C ++。

I am taking a class in C++ programming and the professor told us that there is no need to learn C because C++ contains everything in C plus object-oriented features. However, some others have told me that this is not necessarily true. Can anyone shed some light on this?

解决方案

Overview:

It is almost true that C++ is a superset of C, and your professor is correct in that there is no need to learn C separately.

C++ adds the whole object oriented aspect, generic programming aspect, as well as having less strict rules (like variables needing to be declared at the top of each function). C++ does change the definition of some terms in C such as structs, although still in a superset way.

Examples of why it is not a strict superset:

This Wikipedia article has a couple good examples of such a differences:

One commonly encountered difference is that C allows implicit conversion from void* to other pointer types, but C++ does not. So, the following is valid C code:

int *i = malloc(sizeof(int) * 5);

... but to make it work in both C and C++ one would need to use an explicit cast:

int *i = (int *) malloc(sizeof(int) * 5)

Another common portability issue is that C++ defines many new keywords, such as new and class, that may be used as identifiers (e.g. variable names) in a C program.

This wikipedia article has further differences as well:

C++ compilers prohibit goto from crossing an initialization, as in the following C99 code:

 void fn(void)
 {
  goto flack;
  int i = 1;
 flack:
   ;
 }

What should you learn first?

You should learn C++ first, not because learning C first will hurt you, not because you will have to unlearn anything (you won't), but because there is no benefit in learning C first. You will eventually learn just about everything about C anyway because it is more or less contained in C++.

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