C：警告隐式 long 到 int 转换

发布于 2024-08-11 05:58:39 字数 737 浏览 5 评论 0原文

我想知道是否有办法告诉编译器（我使用的是 gcc 版本 4.1.2 20080704 (Red Hat 4.1.2-46) 或 icc 11.1）在 long 到 int 隐式转换时抛出警告地方。例如，编译包含以下代码的文件 test.c：

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

int main(int argc, char** argv)
{
    int n = atol(argv[1]);
    printf("int: %d\n", n);
    long int N = atol(argv[1]);
    printf("long: %ld\n", N);

    return 0;
}

with:

gcc -Wall -Wconversion test.c -o test

不会产生任何警告。运行生成的二进制文件

./test 12345678901

正如我所预期的那样，

int: -539222987
long: 12345678901

：数字 12345678901 已溢出 int，但未溢出 long。我希望编译器在发生类似情况时告诉我。选项 -Wconversion 出乎意料地（对我来说）不会这样做。

谢谢，

米歇尔

原文

I was wondering whether there is a way to tell the compiler (I'm on gcc version 4.1.2 20080704 (Red Hat 4.1.2-46) or icc 11.1) to throw a warning whenever a long-to-int implicit conversion takes place. For example, compiling the file test.c which contains the code:

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

int main(int argc, char** argv)
{
    int n = atol(argv[1]);
    printf("int: %d\n", n);
    long int N = atol(argv[1]);
    printf("long: %ld\n", N);

    return 0;
}

with:

gcc -Wall -Wconversion test.c -o test

does not produce any warnings. Running the resulting binary as

./test 12345678901

I get, as expected:

int: -539222987
long: 12345678901

as the number 12345678901 has overflown the int but not the long.
I'd like the compiler to tell me whenever something like this might happen. The option -Wconversion unexpectedly (to me) does not do that.

Thanks,

Michele

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