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<title>第六章：输入（二）</title>
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<td width="100%"><font size="3" color="#8000FF"><strong><em>第六章：输入（二）</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">在继续上面的内容时，我想再回顾和强调几个在字符串操作中经常函数：</p>
<p ALIGN="JUSTIFY">先是几个已经接触过的，</font><font SIZE="3">Mid()</font><font FACE="宋体" SIZE="3">，</font><font SIZE="3">Asc()</font><font FACE="宋体" SIZE="3">，</font><font SIZE="3">Len()</font><font FACE="宋体" SIZE="3">，它们的语法分别是：</font><font SIZE="3"></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#004080" SIZE="3">Mid(</font><font color="#004080"><font FACE="宋体" SIZE="3">字符型，起始字符，长度</font>)</font></font><font FACE="宋体" SIZE="3"></p>
</font>
</blockquote>
<font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY">返回子字符串，如果从字符串的第一个字符取起，起始字符为</font><font SIZE="3">1</font><font FACE="宋体" SIZE="3">，依此类推。</font><font SIZE="3"></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#004080">Asc(<font FACE="宋体" SIZE="3">字符型</font>)</font></font><font FACE="宋体" SIZE="3"></p>
</font>
</blockquote>
<font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY">返回数值，如果参数不是一个字符，而是字符串（多个字符），将返回参数的第一个字符</font><font SIZE="3">ASCII</font><font FACE="宋体" SIZE="3">值。</font><font SIZE="3"></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#004080">Len(<font FACE="宋体" SIZE="3">字符型</font>)</font></font><font FACE="宋体" SIZE="3"></p>
</font>
</blockquote>
<font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY">返回字符串的长度。</p>
<p ALIGN="JUSTIFY">下面我再为你解释几个新的函数：</font><font SIZE="3"></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#004080" SIZE="3">Left(</font><font color="#004080"><font FACE="宋体" SIZE="3">字符串，长度</font>)</font></font><font FACE="宋体" SIZE="3"></p>
</font>
</blockquote>
<font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY">将返回字符型，从字符串的第一个字符向左取字符串，与之相对应的是</font><font SIZE="3">Right()</font><font FACE="宋体" SIZE="3">，它将从字符串的最后一个字符向右取字符串。</font><font SIZE="3"></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#004080">Chr(<font FACE="宋体" SIZE="3">数值型</font>)</font></font><font FACE="宋体" SIZE="3"></p>
</font>
</blockquote>
<font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY">该数值范围从</font><font SIZE="3">0</font><font FACE="宋体" SIZE="3">－</font><font SIZE="3">255</font><font FACE="宋体" SIZE="3">，返回字符型，如</font><font SIZE="3">Chr(65)</font><font FACE="宋体" SIZE="3">可返回字符“</font><font SIZE="3">A</font><font FACE="宋体" SIZE="3">”，这样可以输入一些用键盘无法输入的字符。</font><font SIZE="3"></p>
<blockquote>
<p ALIGN="JUSTIFY"><font color="#004080">Str(<font FACE="宋体" SIZE="3">数值型</font>)</font></font><font FACE="宋体" SIZE="3"></p>
</font>
</blockquote>
<font FACE="宋体" SIZE="3"><p ALIGN="JUSTIFY">该函数把数值型转换为字符型，也许你觉得数值“</font><font SIZE="3">123</font><font FACE="宋体" SIZE="3">”和字符串“</font><font SIZE="3">123</font><font FACE="宋体" SIZE="3">”没什么区别，但在内存中一个</font><font SIZE="3">ASCII</font><font FACE="宋体" SIZE="3">字符是占一个字节，也就是说字符串“</font><font SIZE="3">123</font><font FACE="宋体" SIZE="3">”占</font><font SIZE="3">3</font><font FACE="宋体" SIZE="3">个字节，而当数值“</font><font SIZE="3">123</font><font FACE="宋体" SIZE="3">”是整型时，它占两个字符，当它是长整型时，占</font><font SIZE="3">4</font><font FACE="宋体" SIZE="3">个字节。与之向对应的是</font><font SIZE="3">Val(</font><font FACE="宋体" SIZE="3">数值型</font><font SIZE="3">)</font><font FACE="宋体" SIZE="3">，它把数值型转换为字符型。</p>
<p ALIGN="JUSTIFY">上面的函数都是以后要经常用到的，请将它们熟悉。</p>
<p ALIGN="JUSTIFY">上次讲到文本框的用处，还有意思吗？你是否能把上次的程序稍稍变动一下，来计算出输入的单词数，提示一下，单词与单词之间是用空格分隔开的。</p>
<p ALIGN="JUSTIFY">我们继续下面的内容。</font></td>
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