gcc - gcc和g++/gcc-c++有什么区别？

Question

在我看来，gcc可以处理c和c++项目，那么为什么需要g++/gcc-c++？

g++和gcc-c++有什么区别？

Answer 1

如果文件具有适当的扩展名，gcc将C源文件编译为C，将C++源文件编译为C++。但是，它不会自动链接到C++库中。
g++将自动包括C++库；默认情况下，它还将编译带有扩展名的文件，这些扩展名指示它们是C源代码，而不是C语言。

从http://gcc.gnu.org/onlinedocs/gcc/Invoking-G_002b_002b.html#Invoking-G_002b_002b:

C++ source files conventionally use one of the suffixes .C, .cc, .cpp, .CPP, .c++, .cp, or .cxx; C++ header files often use .hh, .hpp, .H, or (for shared template code) .tcc; and preprocessed C++ files use the suffix .ii. GCC recognizes files with these names and compiles them as C++ programs even if you call the compiler the same way as for compiling C programs (usually with the name gcc).

However, the use of gcc does not add the C++ library. g++ is a program that calls GCC and treats .c, .h and .i files as C++ source files instead of C source files unless -x is used, and automatically specifies linking against the C++ library. This program is also useful when precompiling a C header file with a .h extension for use in C++ compilations.

例如，要编译写入 std::cout流的简单C++程序，我可以使用其中一个(在Windows上为MinGW):

g++ -o test.exe test.cpp

gcc -o test.exe test.cpp -lstdc++

但是，如果我尝试:

gcc -o test.exe test.cpp

我在链接时得到 undefined reference 。

而另一个不同之处是以下C程序:

#include <stdlib.h>
#include <stdio.h>

int main() 
{
    int* new;
    int* p = malloc(sizeof(int));

    *p = 42;
    new = p;

    printf("The answer: %d\n", *new);

    return 0;
}

使用以下命令编译并运行良好:

gcc -o test.exe test.c

但是使用以下命令编译时会出现一些错误:

g++ -o test.exe test.c

错误:

test.c: In function 'int main()':
test.c:6:10: error: expected unqualified-id before 'new'
test.c:6:10: error: expected initializer before 'new'
test.c:7:32: error: invalid conversion from 'void*' to 'int*'
test.c:10:9: error: expected type-specifier before '=' token
test.c:10:11: error: lvalue required as left operand of assignment
test.c:12:36: error: expected type-specifier before ')' token