沒有得到中的sprintf

Question

_export int DSPCmdOut(COMMAND_DESCRIPTOR *cmd) 
{ 
    cmd.u[0] = CMD_SG_SYNCHED; 
    cmd.u[1] = uThisStation; 
    cmd.u[2] = iMode; 
    DSPCmdOut(&cmd); 
    return 0; 
} 

_export int DSPCmdOut(COMMAND_DESCRIPTOR *cmd) 
{ 
    if(S->uCMD > (MAX_CMD-1)) 
     return -1; 
    S->cmd[S->uCMD] = *cmd; 
    S->uCMD++; 

    sprintf (cLogLine, "%u,%u,%u: cmd data", cmd.u[0],cmd.u[1],cmd.u[2]);       
    WriteLine (uhGDSLogFile, cLogLine, strlen(cLogLine)); 

    return 0; 
} 

任何數據，我得到這個錯誤而編譯：

Left operand of . has incompatible type 'pointer to COMMAND_DESCRIPTOR'. 

Answer 1

，因爲你正在傳遞一個指向COMMAND_DESCRIPTOR（這是一個結構我想），以賦值結構的字段，你需要對其進行解引用。
因此，cmd->u[0]語法只是一個(*cmd).u[0]。 ->只是一個語法糖。

更改cmd.u[0] = CMD_SG_SYNCHED;到cmd->u[0] = CMD_SG_SYNCHED;等。

這裏是一個不錯的話題：What is the difference between the dot (.) operator and -> in C++?

完整的代碼應該像下面：

_export int DSPCmdOut(COMMAND_DESCRIPTOR *cmd) 
{ 
    cmd->u[0] = CMD_SG_SYNCHED; 
    cmd->u[1] = uThisStation; 
    cmd->u[2] = iMode; 
    DSPCmdOut(&cmd); 
    return 0; 
} 

_export int DSPCmdOut(COMMAND_DESCRIPTOR *cmd) 
{ 
    if(S->uCMD > (MAX_CMD-1)) 
     return -1; 
    S->cmd[S->uCMD] = *cmd; 
    S->uCMD++; 

    sprintf (cLogLine, "%u,%u,%u: cmd data", cmd->u[0],cmd->u[1],cmd->u[2]);       
    WriteLine (uhGDSLogFile, cLogLine, strlen(cLogLine)); 

    return 0; 
}