Pascal if / else程序语法错误 [英] Pascal if/else program syntax error

问题描述

我创建了一个程序来确定二次方程是否给出了一个真实数字作为答案，如果是，它是什么。然而，这是我第一次使用if / else，所以我的程序不会编译过其他的，并且在搜索了半个小时之后我就没有找到为什么
代码如下：

I have created a program to determine if a quadratic equation gives a 'real' number as its answer and if so, what it is. However, this is my first time working with if/else so my program won't compile past the else and, after searching for half an hour I'm no closer to finding out why Code is as follows:

program Quadratic_Equation_Solver;

{$mode objfpc}{$H+}

uses
  Classes, SysUtils, CustApp;
  var
    a, b, c : real;
begin
   writeln('Insert the Value for a please');
   readln(a);
   writeln('Insert the Value for b please');
   readln(b);
   writeln('Insert the Value for c please');
   readln(c);
   if (-4*a*c<b*b) then
      writeln('These variables return an imaginary quantity that');
      writeln('Cannot be computed. Please try again');
      readln;
   (*here it breaks*) else
   Writeln('The Answer is x = ',(-b+sqrt((b*b)-(4*a*c))/(2*a)):8:2);
   readln;
end.

在休息时它说它需要一个分号但是没有效果

At the break it says it needs a semi-colon but that hasn't worked

推荐答案

看起来你错过了开始和结束语句如果和否则部分。编译器需要这些来确定 if 或 else 代码路径中包含哪行代码：

It looks like you're missing a begin and end statement inside your if and else sections. The compiler needs these to determine what line of code is included in the if or the else codepath:

if some condition then
begin
    ...
end
else
begin
    ...
end

所以在你的情况下：

program Quadratic_Equation_Solver;

{$mode objfpc}{$H+}

uses
  Classes, SysUtils, CustApp;
  var
    a, b, c : real;
begin
   writeln('Insert the Value for a please');
   readln(a);
   writeln('Insert the Value for b please');
   readln(b);
   writeln('Insert the Value for c please');
   readln(c);
   if (-4*a*c>b*b) then
   begin
      writeln('These variables return an imaginary quantity that');
      writeln('Cannot be computed. Please try again');
   end
   else
   begin
     Writeln('The Answer is x = ',(-b+sqrt((b*b)-(4*a*c))/(2*a)):8:2);
   end
   readln;
end.

这篇关于Pascal if / else程序语法错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！