A brief talk on some small differences between C and C + + _c language

C + + type checking is more stringent

In C, when the character is passed as a function parameter, the character is used as integral int, sizeof (' c ') = sizeof (int); Further, the C compiler equates the amount of character constants with an integer constant: Putchar (10) is equivalent to Putchar (' \ n ').

However, in C + +, sizeof (' C ') = = 1, supplemented by a point, sizeof (wchar_t) ==4. So it's easy to represent 65,536 different Unicode characters. In addition, in C + +, the difference function depends not only on his function name, but also on its parameters. Therefore, Putchar (10) calls the Putchar (int) version

, Putchar (' \ n ') invokes the Putchar (char) version.

C + + 's function prototype check is more stringent. The function definition in C: void Func (), indicating that the function func () exists, and there is no return value. The declaration does not specify how many formal parameters are specific. But in C + +, it means that it must not have formal parameters passed in!

Main function

In C + +, main functions are mainly written in two ways: int main () and int main (int argc, char** argv);

The return type in the main function is int, not void

If no write return statement is displayed, the default returns 0;

If you write a return statement, you must keep up with an integer value, such as return 1; Write return only; is a serious mistake.

Type checking

When a function is called, the prototype must match strictly. The C language contains stdio.h by default, but C + + does not default to include, so you must include the Cstdio header file. C language Some compiler friendship sponsored the stdio.h.

Function-related differences

Function overload

C + + supports function overloading. The function overload must satisfy the

A. The same function name

B. Different formal parameter lists

C. The attributes of a formal parameter are different, that is, const

At compile time, in fact, for overloaded functions, the internal use of a different name, the professional term is "name mangling", such as void Show (int)--> vshowi, void Show (char*)-->VSHOWCP, such a name.

Formal parameter Default value

The default parameter must appear in the function definition, not in the function implementation.

Code more elegant

Single-line comment, multiple single-line comment in C + +

Null-pointers vs. 0-pointers and nullptr in c++11

All of the 0 values in C + + are 0. In C, NULL represents 0 in the pointer context, and in C + +, you should avoid using NULL, although its macro definition is 0.

C++11 introduced a new keyword nullptr represents a 0-value pointer, which can only be assigned to a pointer type

In C + +, you can use the functions in the C. Runtime Library, but you need to add the extern "C" prefix

In C89, a local variable must be defined at the beginning of a function or statement block! Still using VC6.0 Please note that for your better code career, abandon it. C99 has supported a local definition, which is a big improvement in C. C + + can define local variables anywhere.

In C + +, the struct body can omit the struct keyword when defining the variable

In C + +, the struct body can contain functions, that is, the default properties are public classes

The above is a small series for everyone to talk about C and C + + some of the small differences in all the content, I hope that we support cloud Habitat Community ~