文章目录

• 错误
• 原因
• 解决

错误

错误的意思，是0xff是一个int 类型，要将int 类型赋给char时，会导变窄转换

uniform.cpp: In function ‘int main()’:
uniform.cpp:6:29: error: narrowing conversion of ‘255’ from ‘int’ to ‘char’ inside { } [-Wnarrowing]
  char abc[3]={0xff,0xff,0xff};   、、这里列号是29，是最后一个 0xff，也就是所，赋值的时候，是从后往前来的。right to left。
                             ^
uniform.cpp:6:29: error: narrowing conversion of ‘255’ from ‘int’ to ‘char’ inside { } [-Wnarrowing]
uniform.cpp:6:29: error: narrowing conversion of ‘255’ from ‘int’ to ‘char’ inside { } [-Wnarrowing]
为什么会连报3次呢？因为数组就给了三个初值。

原因

在C++11 及以后的版本，这种变换会被默认检查。
-Wno-narrowing (C++ and Objective-C++ only)
For C++11 and later standards, narrowing conversions are diagnosed by default, as required by the standard.
发生在常量的变窄转换，或者从非常量的变窄转换，会打印警告。
A narrowing conversion from a constant produces an error, and a narrowing conversion from a non-constant produces a warning, but ‘-Wno-narrowing’ suppresses the diagnostic. Note that this does not affect the meaning of well-formed code; narrowing conversions are still considered ill-formed in SFINAE contexts.
With ‘-Wnarrowing’ in C++98, warn when a narrowing conversion prohibited by C++11 occurs within ‘{ }’, e.g.
int i = { 2.2 }; // error: narrowing from double to int

解决

unsigned char abc[3]={0xff,0xff,0xff};