将有符号字符读取为无符号 - 类型提升
考虑这个小程序：
#include <stdio.h>
int main()
{
char c = 0xFF;
printf("%d\n", c);
return 0;
}
它的输出是 -1，正如预期的那样（考虑到 char 在我的 系统）。我想做的是让它打印255。这是属于 当然是真实情况的简化，我不能仅仅定义 c 为无符号。
第一个可能的更改是使用 %u 作为格式化程序，但是 通常的类型提升规则适用于此，并且数字打印为 232 - 1.
那么有没有什么方法可以将签名字符读取为无符号之前 提升为 int？我可以创建一个指向无符号字符集的指针 c 的地址，稍后取消引用它，但不确定这是否是最好的 方法。
Consider this little program:
#include <stdio.h>
int main()
{
char c = 0xFF;
printf("%d\n", c);
return 0;
}
Its output is -1, as expected (considering char is signed in my
system). What I'm trying to do is to make it print 255. This is of
course a simplification of the real situation, where I can't just definec as unsigned.
The first possible change would be using %u as formatter instead, but
the usual type promotion rules apply here, and the number is printed as
232 - 1.
So is there any way to read the signed char as unsigned before it gets
promoted to an int? I could create a pointer to a unsigned char set to the
address of c, and dereference it later, but not sure if this is the best
approach.
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c正在使用签名的升级规则进行升级。将c强制转换为 unsigned 以使用无符号提升。unsigned char 将提升为 unsigned int。
cis being promoted using signed promotion rules. Castcto unsigned to use unsigned promotion.Unsigned char will be promoted to unsigned int.