编译以下代码:
double getDouble()
{
double value = 2147483649.0;
return value;
}
int main()
{
printf("INT_MAX: %u\n", INT_MAX);
printf("UINT_MAX: %u\n", UINT_MAX);
printf("Double value: %f\n", getDouble());
printf("Direct cast value: %u\n", (unsigned int) getDouble());
double d = getDouble();
printf("Indirect cast value: %u\n", (unsigned int) d);
return 0;
}
输出(MSVC X86):
INT_MAX: 2147483647
UINT_MAX: 4294967295
Double value: 2147483649.000000
Direct cast value: 2147483648
Indirect cast value: 2147483649
输出(MSVC X64):
INT_MAX: 2147483647
UINT_MAX: 4294967295
Double value: 2147483649.000000
Direct cast value: 2147483649
Indirect cast value: 2147483649
在Microsoft documentation中，从double到unsigned int的转换中没有提到有符号整数的最大值.
当返回函数时，所有大于INT_MAX的值都将被截断为2147483648.
我用Visual Studio 2019来建立这个程序.这不会发生在gcc.
我做错什么了吗？有没有安全的方法将double转化为unsigned int？