g++ 可变大小数组没有警告? [英] g++ variable size array no warning?

问题描述

int a;
cin >> a;
int ints[a];

为什么这在编译时不会抛出任何警告?我怎么知道这个数组什么时候实际使用的是堆还是栈?

Why does this not throw any kind of warning while compiling? How do I know when this array thing is actually using the heap or the stack?

g++ -std=c++11 -Wall *.cpp -o main

推荐答案

ISO C++ 不允许使用变长数组，g++ 很高兴地告诉你，如果你增加通过向它传递 -pedantic 标志来严格它.

ISO C++ disallows the use of variable length arrays, which g++ happily tells you if you increase the strictness of it by passing it the -pedantic flag.

使用 -pedantic 将发出有关违反标准的警告.如果您希望 g++ 发出错误并因此拒绝编译；使用 -pedantic-errors.

Using -pedantic will issue a warning about things breaking the standard. If you want g++ to issue an error and with this refuse compilation because of such things; use -pedantic-errors.

g++ -Wall -pedantic -std=c++11 apa.cpp

apa.cpp: In function ‘int main(int, char**)’:
apa.cpp:8:13: warning: ISO C++ forbids variable length array ‘ints’ [-Wvla]
   int ints[a];
             ^
apa.cpp:8:7: warning: unused variable ‘ints’ [-Wunused-variable]
   int ints[a];
       ^

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