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<title>第六章:输入(一)</title>
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<td width="100%"><font size="3" color="#8000FF"><strong><em>第六章:输入(一)</em></strong></font></td>
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<td width="100%" style="background-color: rgb(232,255,254)"><font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY"></font><font size="3">我们为什么要设计计算机程序呢,当然是为了计算机能为我们完成工作,但是要完成不同的任务,我们就必须对计算机下达命令,然后计算机在把信息返馈回来――任务是否完成。以上就是所谓的人机对话或交互功能,尤其是在Windows操作里我们需要进行更多的输入工作,我们需要填写各种各样的表格,设置程序的重要参数,把数据输入给计算机,再又它完成既定的工作就是今天我们本章要重点讨论的问题――在VB中如何建立完整的输入机制。</font></p>
<p ALIGN="JUSTIFY"><font size="3">在VB中提供了一个函数InputBox能帮助我们建立一个最简单的输入窗体,语法如下:</font></p>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>InputBox(prompt[,title][,default][,xpos][,ypos][,helpfile,context])</em></strong></font></p>
<p ALIGN="JUSTIFY"><font size="3">该函数返回一个字符串表达式,其参数含义为:(“[]”表示可缺省)</font></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>prompt――字符串表达式,最大长度为1024字符,窗体上的提示部分。</em></strong></font></p>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>Title――字符串表达式,显示标题栏里的文本。</em></strong></font></p>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>Default――字符串表达式,窗体中文本框的缺省值。</em></strong></font></p>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>xpos,ypos――数值表达式,以Twips为单位指定窗体出现在屏幕上的位置。</em></strong></font></p>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>helpfile――字符串表达式,是帮助文件的完整路径。</em></strong></font></p>
<p ALIGN="JUSTIFY"><font color="#000080" size="3"><strong><em>Context――数值表达式,指定适合的帮助主题。</em></strong></font></p>
</blockquote>
<p ALIGN="JUSTIFY"><font size="3">可能你看了上面的说明并不明白,那么下面我们就用Input语句完成一个最简单的程序。</font></p>
<p ALIGN="JUSTIFY"> </p>
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<p ALIGN="JUSTIFY"><font color="#FF0000" size="3"><strong><em>小知识:屏幕坐标</em></strong></font></p>
<p ALIGN="JUSTIFY"><font color="#FF0000" size="3"><strong><em>在计算机的屏幕上也有一个类似于我们在中学里常用到的直角坐标系,之不过它的原点不在左下,而是在屏幕的右上角,屏幕的最右上方坐标为(0,0),它的横坐标和我们的习惯是一致的,而纵坐标则是越向下越大,不仅是屏幕,所有的对象里都是一样,需要记清。见图6-1</em></strong></font></p>
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