sec4-2.htm

Fortran77和90/95编程入门,用于教学

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>用字符型变量作为过程<span class=GramE>的哑元时</span>，可以用正整数作长度，也可以把</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>*</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>作长度，后者可以与任何长度的实元<span class=GramE>作哑实结合</span>，相当于以实元的具体长度<span
class=GramE>为哑元的</span>长度。</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>CHARACTER</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>后面说明的长度是其后所有实体名的公共长度，如果某一变量的长度与其它不同，可以在其变量名后标出自己的特有长度，方法是在变量名后写上</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>*</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>及长度。<span class=GramE>例加</span>：</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
class=GramE><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>CHARACTER(</span></span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>LEN=12) :: A,B*5,C,D*7,E<o:p></o:p></span></p>

<p style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l2 level1 lfo4;
tab-stops:list 18.0pt;text-autospace:none'><a name="第4_2_2b"></a><![if !supportLists]><span
lang=EN-US style='font-family:宋体;mso-bidi-font-family:宋体;color:red'><span
style='mso-list:Ignore'>b)<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]><span lang=ZH-CN style='font-family:宋体;
color:red'>字符子串</span><span lang=EN-US style='font-family:宋体;color:red'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none;mso-char-indent-size:12pt'><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>字符数据中某一部分相连的字符为<span class=GramE>字符子串</span>，也可以作为一个实体与字符变量一样参加操作。<span
class=GramE>字符子串的</span>一般形式是：</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体;color:#FF9900'>V(e1:e2)</span><span lang=ZH-CN style='font-size:
12.0pt;font-family:宋体'>。</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'>V</span><span lang=ZH-CN style='font-size:12.0pt;font-family:
宋体'>是字符型实体名，包括字符变量名、字符函数名、字符数组元素等等。</span><span lang=EN-US style='font-size:
12.0pt;font-family:宋体'>e1,e2</span><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>是整型表达式<span class=GramE>或正整常数</span>，</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>e1</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的值指明子串在</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>V</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>中的<span class=GramE>起始列号</span>，</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>e2</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的值指明子串在</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>V</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>中的<span class=GramE>终止列号</span>。如果</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>e1</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>省略，表示<span class=GramE>子串从</span>第一个<span
class=GramE>字符取起</span>；</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'>e2</span><span lang=ZH-CN style='font-size:12.0pt;font-family:
宋体'>省略，<span class=GramE>表示子串取到</span>末尾；如</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>e1,e2</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>都省略，表示<span class=GramE>子串从头</span>取到尾。例如：设有字符变量</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>，其取值为‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>ABCDE12345FGH</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’，则下面<span class=GramE>的子串取值</span>为：</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A(3:11) <span
style='mso-spacerun:yes'>&nbsp;</span><span
style='mso-spacerun:yes'>&nbsp;&nbsp;</span>-&gt;<span
style='mso-spacerun:yes'>&nbsp; </span></span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>CDE12345F</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’，</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A(I+4:9) <span
style='mso-spacerun:yes'>&nbsp;</span><span
style='mso-spacerun:yes'>&nbsp;</span>-&gt;<span
style='mso-spacerun:yes'>&nbsp; </span></span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>E1234</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>(I=1)</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>，‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>1234</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>(I=2)<o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A(:5)<span
style='mso-spacerun:yes'>&nbsp;&nbsp;&nbsp;&nbsp; </span><span
style='mso-spacerun:yes'>&nbsp;</span>-&gt;<span
style='mso-spacerun:yes'>&nbsp; </span></span><span class=GramE><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>‘</span></span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>ABCDE</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>’</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A(11:)<span
style='mso-spacerun:yes'>&nbsp;&nbsp;&nbsp;&nbsp; </span>-&gt;<span
style='mso-spacerun:yes'>&nbsp; </span></span><span class=GramE><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>‘</span></span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>FGH</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A(:)<span
style='mso-spacerun:yes'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>-&gt;<span
style='mso-spacerun:yes'>&nbsp; </span></span><span class=GramE><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>‘</span></span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>ABCDE12345FGH</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>’</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:57.7pt;mso-char-indent-count:4.81;
line-height:15.0pt;mso-line-height-rule:exactly;text-autospace:none'><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A(3:3)<span
style='mso-spacerun:yes'>&nbsp;&nbsp;&nbsp; </span><span
style='mso-spacerun:yes'>&nbsp;</span>-&gt;<span
style='mso-spacerun:yes'>&nbsp; </span></span><span class=GramE><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>‘</span></span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>C</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>子串在程序中可直接引用，也可被其它字符实体再赋值，因此可使程序员任意地取出一部分字符，并按需要替换一部分字符，非常灵活。例如：</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>PRINT *</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>，</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>(A(I:I</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>＋</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>1),I=6,9)</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>，可以打印‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>12</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’、‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>23</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’、‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>34</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’、‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>45</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>’。</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l2 level1 lfo4;
tab-stops:list 18.0pt;text-autospace:none'><a name="第4_2_2c"></a><![if !supportLists]><span
lang=EN-US style='font-family:宋体;mso-bidi-font-family:宋体;color:red'><span
style='mso-list:Ignore'>c)<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]><span lang=ZH-CN style='font-family:宋体;
color:red'>字符操作与赋值</span><span lang=EN-US style='font-family:宋体;color:red'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none;mso-char-indent-size:12pt'><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>字符操作符只有一个，称<span style='color:fuchsia'>并置符</span>，为两相连的斜杠“</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>//</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>”，其功能是把前后两个字符串拼连在一起。表达式中的操作对象可以是字符变量，字符常数、<span
class=GramE>字符子串</span>、字符函数值、字符数组元素等。例如：</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>AB</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman";letter-spacing:-4.0pt'>’</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>/<span style='letter-spacing:
-4.0pt'>/</span></span><span lang=ZH-CN style='font-size:12.0pt;font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>‘</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>CDE</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>’</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的值<span style='letter-spacing:-2.0pt'>为</span>‘</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>ABCDE</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>’。</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>C/<span style='letter-spacing:-4.0pt'>/</span></span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>‘</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>ABC</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体;letter-spacing:-4.0pt'>’</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>//A(2:6)//B(1:4)//D</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>是把几个字符串连在一起。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>字符赋值语句的一般形式是：<span
style='color:#FF9900'>字符变量＝字符表达式</span>。在字符赋值语句中，要求两边种别<span class=GramE>值一致</span>，此外还有长度问题。当两边长度不等时，赋值时以左边的字符变量说明长度为准，当右边小于左边时，尾部补空格，否则将右边尾部的多余部分截去。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l2 level1 lfo4;
tab-stops:list 18.0pt;text-autospace:none'><a name="第4_2_2d"></a><![if !supportLists]><span
lang=EN-US style='font-family:宋体;mso-bidi-font-family:宋体;color:red'><span
style='mso-list:Ignore'>d)<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]><span lang=ZH-CN style='font-family:宋体;
color:red'>字符比较</span><span lang=EN-US style='font-family:宋体;color:red'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none;mso-char-indent-size:12pt'><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>对每种机器，系统都把本机上可以使用的各种字符按先后排列成某种次序，每个字符在排序中有确定的位置，称为<span
style='color:fuchsia'>排序号</span>。有了排序号，字符之间就可以比较大小及相等与否，组成关系表达式。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>各种系统字符排序不一样，同一字符，在不同机上排序<span
class=GramE>值可能</span>不一样。以</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'>ASCII</span><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>码为例，有</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'>128</span><span lang=ZH-CN style='font-size:12.0pt;font-family:
宋体'>个字符，它的第一个字符序号为零，最后一个序号为</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'>127</span><span lang=ZH-CN style='font-size:12.0pt;font-family:
宋体'>。例如</span><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>A</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>的排序号为</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>65</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>，数码</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>0</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的排序号为</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>32</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>。序号</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>0</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>～</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>31</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>及序号</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>127</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的字符称为控制字符，用来控制操作，它们是非打印字符，屏幕上不可见，通常编程时可于忽略。从</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>ASCII</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>码字符集的排序可以看出，小写英文字母排序在大写英文字母之后，它们的序号不同。因此，虽然在书写</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>FORTRAN</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>语句时，大小写字母是等价的，但当进行字符操作和字符比较时必须看成是不同的。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>

<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-layout-grid-align:none;
text-autospace:none'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>字符作比较实际上是比较它们的序号大小。字符比较的一般形式是两端为字符表达式的关系表达式：<span
style='color:#FF9900'>＜字符表达式＞＜关系操作符＞＜字符表达式＞</span>。例如</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman";letter-spacing:-4.0pt'>：</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;