c++解决⽆法打印uint8_t类型变量的问题将uint8_t 转化为unsigned 类型
使⽤⼀元运算符+(和- 运算符对应)
测试代码如下
#include <cstdint>
#include <iostream>
#include <typeinfo>
int main()
{
std::uint8_t uint8_num = 10;
std::cout << "uint8_t num is " << uint8_num << std::endl; //⽆法打印
std::cout << "after cast to unsigned, uint8_t num is " << unsigned(uint8_num) << std::endl; //能正常打印
std::cout << "with a unary + operator, uint8_t num is " << +uint8_num << std::endl; //能正常打印
std::cout << "type of '+uint8_num' is " << typeid(+uint8_num).name() << std::endl;
return 0;
}
运⾏结果如下
可见使⽤+运算符的原理也是进⾏类型转换(把uint8_t 转为 int)
补充知识：C 语⾔printf打印各种数据类型的⽅法(u8/s8//u64/double/float)(全)
⾸先必须知道u8,s8等数据类型的定义：
typedef signed char s8;
typedef unsigned char u8;
typedef signed short s16;
typedef unsigned short u16;
typedef signed int s32;
typedef unsigned int u32;
typedef signed long long s64;
typedef unsigned long long u64;
与体系结构相关的，定义在include/linux/type.h⽂件中：
/* bsd */
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;
typedef unsigned long u_long;
/* sysv */
typedef unsigned char unchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
#ifndef __BIT_TYPES_DEFINED__
#define __BIT_TYPES_DEFINED__
typedef __u8 u_int8_t;
typedef __s8 int8_t;
typedef __u16 u_int16_t;
typedef __s16 int16_t;
typedef __u32 u_int32_t;
typedef __s32 int32_t;
#endif /* !(__BIT_TYPES_DEFINED__) */
typedef __u8 uint8_t;
typedef __u16 uint16_t;
typedef __u32 uint32_t;
#if defined(__GNUC__)
typedef __u64 uint64_t;
typedef __u64 u_int64_t;
typedef __s64 int64_t;
对于各种数据类型的打印⽅式总结如下如下：
数据类型打印格式
u8%d
s8%d
u16%d or %hu
s16%d or %hd
u32%u
s32%d
u64%llu
s64%lld
int%d
unsigned int%u
short int%d or %hd
long%ld
unsigned long%lu
long long%lld
unsigned long long%llu
char%c
char *%s
bool (#define stdbool.h)%d
unsigned int/int------>⼗六进制%0x
unsigned long/long---->⼗六进制%0lx
long long/unsigned long long ----->⼗六进制%0llx
unsigned int/int------>⼋进制%0o
unsigned long/long---->⼋进制%0lo
long long/unsigned long long ----->⼋进制%0llo
float%f
double%f or %lf
科学技术类型(必须转化为double类型)%e
限制输出字段宽度%x.yf (x：整数长度,y:⼩数点长度)
待解问题，在linux kernel⾥⾯也有使⽤bool来定义变量，查看code，定义如下：typedef _Bool bool;
但是并没有真正到具体定义在何处，待解。
下⾯是stdbool.h的source code：
#define _STDBOOL_H
#ifndef __cplusplus
#define bool _Bool
#define true 1
#define false 0
#else /* __cplusplus */
/* Supporting _Bool in C++ is a GCC extension. */
#define _Bool bool
#if __cplusplus < 201103L
/* Defining these macros in C++98 is a GCC extension. */
#define bool bool
#define false false
#define true true
#endif
#endif /* __cplusplus */
/* Signal that all the definitions are present. */
printf输出格式 unsigned short#define __bool_true_false_are_defined 1
#endif /* stdbool.h */
也⼤致解释了linux kernel bool type了。
以上这篇c++ 解决⽆法打印uint8_t 类型变量的问题就是⼩编分享给⼤家的全部内容了，希望能给⼤家⼀个参考，也希望⼤家多多⽀持。

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