小编Rav*_*avo的帖子

所以我有一些语法错误说:

Error C2143 syntax error: missing ';' before '* '  
Error C4430 missing type specifier - int assumed. Note: C++ does not support default-int  
Error C2238 unexpected token(s) preceding ';'  
Error C2143 syntax error: missing ';' before '*'  

所有这些都在:

#pragma once  
#include "World.h"  
class Organism  
{  
protected:  
    int strength;
    int initiative;    
    int age, x, y;  
    char sign;  
    World *world;  //line that makes errors
public:  
    Organism(World*,int,int);
    virtual ~Organism();
    virtual void action() = 0;
    virtual void collision() = 0;
    virtual char getSign() …

为什么会出现此错误？

“ ADA.FLOAT_IO”不是预定义的库单元

我以前从未在ADA中写过任何东西，只是我不知道自己在做什么。我使用GNAT进行编译。

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Float_IO; use Ada.Float_IO;
with Ada.Numerics.Elementary_Functions;
use Ada.Numerics.Elementary_Functions;

procedure MAIN is
   A,B,C:Float;
   W : Float;
   Re, Im:Float;
begin
   Put("Give A");Get(A);
   Put("Give B");Get(B);
   Put("Give C");Get(C);New_Line;
   if A=0.0 then
      Put_Line("It is not second degree polynomial");
   else
      W:=B*B - 4.0*A*C;
      Re:=B/(2.0*A); Im:=Sqrt(Abs(W))/(2.0*A);
      Put("dif = "); Put(W);New_Line;
      if W<0.0 then
         Put_Line("Complex ");
         Put("x1 = ");Put(-Re);Put(" -j ");Put(Im);Put(" ");
         Put("x2 = ");Put(-Re);Put(" +j ");Put(Im);New_Line;
      else
         Put_Line("Real");
         Put("x1 = ");Put(-Re-Im);Put(" ");
         Put("x2 = ");Put(-Re+Im);
      end if;
   end if; …

如何使用按钮制作简单的网格视图？我已经尝试了最明显的解决方案，但它不起作用。教程真的很糟糕（对我来说），而且简单的解决方案不起作用。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
  <GridView
      android:id="@+id/gridView"
      android:layout_width="match_parent"
      android:layout_height="155.5dp"
      android:numColumns="2"
      android:padding="10dp"
      android:layout_marginBottom="68.0dp"
      android:background="#009967">
      <Button
        android:text="Button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button1" />
  </GridView>

</LinearLayout>