gcc 编译 C++ 代码:未定义对 `operator new[](unsigned long long)' 的引用 [英] gcc compiling C++ code: undefined reference to `operator new[](unsigned long long)'

问题描述

There's a C++ code:

#include <stdio.h>

int main() {

int b = sizeof('a');
if(b==4) printf("I'm a C program!
");
else printf("I'm a C++ program!
");
}

Compile it like this:

gcc main.cpp -o main

It succeeds and gives:

I'm a C++ program!

Then add a line somewhere inside function main

int *p1 = new int [1000];

It fails with:

C:Users...AppDataLocalTempcccJZ8kN.o:main1.cpp:(.text+0x1f): undefined reference to operator new[](unsigned long long)'
collect2.exe: error: ld returned 1 exit status

Then the following two commands successfully compile the code:

gcc main.cpp -o main -lstdc++

and

g++ main.cpp -o main

The compiler is minGW-win64 (http://mingw-w64.sourceforge.net/).

The questions are:

1. Which of the two last commands are better?
2. To my mind gcc correctly chooses the right compiler but then uses a wrong linker. Is it right?
3. May it be a problem in minGW-win64?

As I see (correct me if it's wrong) gcc was intended to be a main program that takes the input and decides what to do with it. So I'd better use gcc if it worked without -lstdc++. But if it's not possible I'll prefer using g++ instead as don't know what else gcc may miss.

Many thanks for your considerations

解决方案

gcc is the GCC compiler-driver for C programs, g++ is the one for C++ programs.
Both will guess the language on the basis of the file-extension, unless overridden.

But if you use the wrong driver, the default-options will be wrong, like leaving out the C++ standard-library for C++ programs compiled with gcc when linking.

You can add just the library with -lstdc++, though using the proper driver is preferable, as plain gcc may be missing other, subtler options.

这篇关于gcc 编译 C++ 代码:未定义对 `operator new[](unsigned long long)' 的引用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！