C++格式掩码没有命名类型

C++ rmask does not name a type

本文关键字：类型 格式 掩码 C++      更新时间：2023-10-16

我有来自sdl2文档的以下代码：

//Color declartions for later
Uint32 rmask, gmask, bmask, amask;
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    rmask = 0xff000000;
    gmask = 0x00ff0000;
    bmask = 0x0000ff00;
    amask = 0x000000ff;
#else
    rmask = 0x000000ff;
    gmask = 0x0000ff00;
    bmask = 0x00ff0000;
    amask = 0xff000000;
#endif

代码块告诉我这个条件是真的，但在编译时，它告诉我rmask不命名类型。错误标记为从else语句的第一行开始。首先，我该如何避免这种情况？其次，我甚至需要if语句吗？

完整的错误日志为：

||=== Build: Debug in hayfysh (compiler: GNU GCC Compiler) ===|
/home/andrew/hayfysh/main.cpp|57|error: ‘rmask’ does not name a type|
/home/andrew/hayfysh/main.cpp|58|error: ‘gmask’ does not name a type|
/home/andrew/hayfysh/main.cpp|59|error: ‘bmask’ does not name a type|
/home/andrew/hayfysh/main.cpp|60|error: ‘amask’ does not name a type|
/home/andrew/hayfysh/main.cpp||In function ‘int newWindow(int, int, bool, const char*)’:|
/home/andrew/hayfysh/main.cpp|90|error: cannot convert ‘const char*’ to ‘FILE* {aka _IO_FILE*}’ for argument ‘1’ to ‘int fprintf(FILE*, const char*, ...)’|
||=== Build failed: 5 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

已通过将fprintf更改为printf 修复了第五个错误

假设这段代码正是问题发生的地方（即，它不是从函数中间提取的），那么问题是全局范围内不允许使用赋值语句。将其更改为初始化变量（是否应将其标记为常量？）：

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    Uint32 rmask = 0xff000000;
    Uint32 gmask = 0x00ff0000;
    Uint32 bmask = 0x0000ff00;
    Uint32 amask = 0x000000ff;
#else
    Uint32 rmask = 0x000000ff;
    Uint32 gmask = 0x0000ff00;
    Uint32 bmask = 0x00ff0000;
    Uint32 amask = 0xff000000;
#endif
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