无法将 C 中的位域初始化为全局

Question

我已经声明了一个位域，如下所示。

struct  {
    volatile uint8_t screenflag:1;
    volatile uint8_t logoflag:1;
    volatile uint8_t oledflag:1;
    volatile uint8_t animationflag:1;
    volatile uint8_t clockdialflag:1;
    volatile uint8_t update_screen:1;
    volatile uint8_t BLE_activity:1;
    uint8_t ble_status:1;
} oled_flag;

但是当我试图从 Main() 函数中初始化 Bitfield 的元素时，它在编译时显示以下错误。

....\Src\main.c(95): warning: #77-D: this declaration has no storage class or type specifier oled_flag.screenflag=1; ....\Src\main.c(95): error: #147: declaration is incompatible with "struct oled_flag" (declared at line 92)
oled_flag.screenflag=1; ....\Src\main.c(95): error: #65: expected a ";" oled_flag.screenflag=1; ....\Src\main.c(96): warning: #77-D: this declaration has no storage class or type specifier
oled_flag.logoflag=0; ....\Src\main.c(96): error: #147: declaration is incompatible with "struct oled_flag" (declared at line 95) oled_flag.logoflag=0; ....\Src\main.c(96): error: #65: expected a ";" oled_flag.logoflag=0; ....\Src\main.c(97): warning:

77-D: this declaration has no storage class or type specifier oled_flag.oledflag=1; ....\Src\main.c(97): error: #147: declaration

is incompatible with "struct oled_flag" (declared at line 96) oled_flag.oledflag=1; ....\Src\main.c(97): error: #65: expected a ";" oled_flag.oledflag=1; ....\Src\main.c(98): warning:

77-D: this declaration has no storage class or type specifier oled_flag.animationflag=0; ....\Src\main.c(98): error: #147:

declaration is incompatible with "struct oled_flag" (declared at line 97) oled_flag.animationflag=0; ....\Src\main.c(98): error: #65: expected a ";"
oled_flag.animationflag=0; ....\Src\main.c(99): warning: #77-D: this declaration has no storage class or type specifier
oled_flag.clockdialflag=1; ....\Src\main.c(99): error: #147: declaration is incompatible with "struct oled_flag" (declared at line 98) oled_flag.clockdialflag=1; ....\Src\main.c(99): error: #65: expected a ";"
oled_flag.clockdialflag=1; ....\Src\main.c(100): warning: #77-D: this declaration has no storage class or type specifier

等..

初始化代码为:

oled_flag.screenflag=1;
oled_flag.logoflag=0;
oled_flag.oledflag=1;
oled_flag.animationflag=0;
oled_flag.clockdialflag=1;
oled_flag.update_screen=0;
oled_flag.BLE_activity=0;
oled_flag.ble_status=1;

但是当我在 Main() 函数中初始化位域的元素时，它工作正常。

Answer 1

C 中不能在函数外有语句。您需要将语句移动到函数内或将全局变量与其声明一起初始化:

struct  {
    volatile uint8_t screenflag:1;
    volatile uint8_t logoflag:1;
    volatile uint8_t oledflag:1;
    volatile uint8_t animationflag:1;
    volatile uint8_t clockdialflag:1;
    volatile uint8_t update_screen:1;
    volatile uint8_t BLE_activity:1;
    uint8_t ble_status:1;
} oled_flag = {
    .screenflag = 1,
    .logoflag = 0,
    .oledflag = 1,
    .animationflag = 0,
    .clockdialflag = 1,
    .update_screen = 0,
    .BLE_activity = 0,
    .ble_status = 1
};