C语言 | Switch的错误用法

C语言 | Switch的错误用法

1.示例(问题)

void FlowWndPlay_DownKey3Ctrl(void)
{
  switch (g_PlbData.State)
  {
        case PLB_ST_PLAY_MOV:
        case PLB_ST_FWD_MOV:
        case PLB_ST_BWD_MOV:
      {
            UxStatic_SetData(&UIFlowWndPlay_VKEY3CCtrl, STATIC_VALUE, ICON_IC_BAR_PLAY);
          break;
      }
      case PLB_ST_PAUSE_MOV:
      {
            UxStatic_SetData(&UIFlowWndPlay_VKEY3CCtrl, STATIC_VALUE, ICON_IC_BAR_RIGHT_OFF);
          break;
      }
      case PLB_ST_FULL:
      {
            UxStatic_SetData(&UIFlowWndPlay_VKEY3CCtrl, STATIC_VALUE, ICON_IC_BAR_RIGHT);
          break;
      }
        UxCtrl_SetShow(&UIFlowWndPlay_VKEY3CCtrl, TRUE);
  }
}

实际运行时，当​​case​​​里面匹配执行后；​​UxCtrl_SetShow(&UIFlowWndPlay_VKEY3CCtrl, TRUE)​​这一句将不会运行，这就脱离了我们的实际目的。

改写如下：

void FlowWndPlay_UpKey2Ctrl(void)
{
    UINT32 uiPBFileFmt;
    PB_GetParam(PBPRMID_CURR_FILEFMT, &uiPBFileFmt);

    switch (g_PlbData.State)
    {
        case PLB_ST_PLAY_MOV:
        case PLB_ST_FWD_MOV:
        case PLB_ST_BWD_MOV:
        {
            UxStatic_SetData(&UIFlowWndPlay_VKEY2CCtrl, STATIC_VALUE, ICON_IC_BAR_PLAY_FAST);
            break;
        }
        case PLB_ST_PAUSE_MOV:
        {
            UxStatic_SetData(&UIFlowWndPlay_VKEY2CCtrl, STATIC_VALUE, ICON_IC_BAR_LEFT_OFF);
            break;
        }
        case PLB_ST_FULL:
        {
            UxStatic_SetData(&UIFlowWndPlay_VKEY2CCtrl, STATIC_VALUE, ICON_IC_BAR_LEFT);
            break;
        }
    }

    if (uiPBFileFmt & PBFMT_JPG){
        UxStatic_SetData(&UIFlowWndPlay_VKEY2CCtrl, STATIC_VALUE, ICON_IC_BAR_MENU);
    }

    UxCtrl_SetShow(&UIFlowWndPlay_VKEY2CCtrl, TRUE);
}

2.实验

测试1：

#include <stdio.h>

int main(int argc, char* argv[])
{
    int a = 2;

    switch(a)
    {
        case 1:
        printf("1\n");
            break;

        case 2:
        printf("2\n");
            break;

        printf("3\n");
    }

    return 0;
}

运行：

[lanfeiye@fly-vm cStudy]$ ./testSwitch
2

测试2：

#include <stdio.h>

int main(int argc, char* argv[])
{
    int a = 3;

    switch(a)
    {
        case 1:
        printf("1\n");
            break;

        case 2:
        printf("2\n");
            break;

        printf("3\n");
    }

    printf("4\n");

    return 0;
}

运行：

[lanfeiye@fly-vm cStudy]$ make testSwitch
gcc -o testSwitch testSwitch.c -g -Wall
[lanfeiye@fly-vm cStudy]$ ./testSwitch
4