📄 5_2.htm
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<p class=MsoNormal style='margin-left:21.0pt;text-indent:-21.0pt;mso-list:l2 level1 lfo1;
tab-stops:list 21.0pt'> <span lang=EN-US style='font-family:
Wingdings'>l<span style='font:7.0pt "Times New Roman"'>
</span></span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>这里函数</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>num2str</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>用来把数值转换成字符串，字符串连接用来把所转换的数嵌人到一个字符串句子中。按类似方式，</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>int2str</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>把整数转换成字符串。无论是</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>num2str</span></b><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>还是</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>int2str</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>都调用函数</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>sprintf</span></b><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>，它用类似</span><span
lang=EN-US>C</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>语言语法把数值转换成字符串。请注意函数</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>str2num</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>不能接受用户定义的变量，也不能执行转换过程的算术运算。</span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>?s='he is a student';<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>?a=abs(s)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>a =<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'><span style="mso-spacerun: yes"> </span>Columns 1 through 12 <o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'><span style="mso-spacerun: yes"> </span>104<span
style="mso-spacerun: yes"> </span>101<span style="mso-spacerun:
yes"> </span>32<span style="mso-spacerun: yes">
</span>105<span style="mso-spacerun: yes"> </span>115<span
style="mso-spacerun: yes"> </span>32<span
style="mso-spacerun: yes"> </span>97<span
style="mso-spacerun: yes"> </span>32<span
style="mso-spacerun: yes"> </span>115<span style="mso-spacerun:
yes"> </span>116<span style="mso-spacerun: yes">
</span>117<span style="mso-spacerun: yes"> </span>100<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'><span style="mso-spacerun: yes"> </span>Columns 13 through 15 <o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'><span style="mso-spacerun: yes"> </span>101<span
style="mso-spacerun: yes"> </span>110<span style="mso-spacerun:
yes"> </span>116<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>?num2str(a)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>ans =<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>104<span style="mso-spacerun: yes"> </span>101<span
style="mso-spacerun: yes"> </span>32<span style="mso-spacerun:
yes"> </span>105<span style="mso-spacerun: yes"> </span>115<span
style="mso-spacerun: yes"> </span>32<span style="mso-spacerun:
yes"> </span>97<span style="mso-spacerun: yes">
</span>32<span style="mso-spacerun: yes"> </span>115<span
style="mso-spacerun: yes"> </span>116<span style="mso-spacerun:
yes"> </span>117<span style="mso-spacerun: yes"> </span>100<span
style="mso-spacerun: yes"> </span>101<span style="mso-spacerun:
yes"> </span>110<span style="mso-spacerun: yes"> </span>116<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>?int2str(s)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>ans =<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>104<span style="mso-spacerun: yes"> </span>101<span
style="mso-spacerun: yes"> </span>32<span style="mso-spacerun:
yes"> </span>105<span style="mso-spacerun: yes"> </span>115<span
style="mso-spacerun: yes"> </span>32<span style="mso-spacerun:
yes"> </span>97<span style="mso-spacerun: yes">
</span>32<span style="mso-spacerun: yes"> </span>115<span
style="mso-spacerun: yes"> </span>116<span style="mso-spacerun:
yes"> </span>117<span style="mso-spacerun: yes"> </span>100<span
style="mso-spacerun: yes"> </span>101<span style="mso-spacerun:
yes"> </span>110<span style="mso-spacerun: yes"> </span>116</span></p>
<p class=MsoNormal style='margin-left:21.0pt;text-indent:-21.0pt;mso-list:l2 level1 lfo1;
tab-stops:list 21.0pt'> <span lang=EN-US style='font-family:
Wingdings'>l<span style='font:7.0pt "Times New Roman"'>
</span></span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>函数</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>disp</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>允许不打印它的变量名而显示一个字符串。</span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>?disp(s)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>he is a student</span></p>
<p class=MsoNormal style='margin-left:21.0pt;text-indent:-21.0pt;mso-list:l2 level1 lfo1;
tab-stops:list 21.0pt'><span lang=EN-US style='font-family:
Wingdings'>l<span style='font:7.0pt "Times New Roman"'>
</span></span> <span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>函数</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>find</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>用来找出小写字符的下标值，然后，从小写元素中只减去小写与大写之差，最后，用</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>setstr</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>把求得的数组转换成它的字符串表示。</span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>?find(s>'m')<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'>ans =<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:2.0gd'><span lang=EN-US style='color:
blue'><span style="mso-spacerun: yes"> </span>5<span
style="mso-spacerun: yes"> </span>9<span
style="mso-spacerun: yes"> </span>10<span
style="mso-spacerun: yes"> </span>11<span
style="mso-spacerun: yes"> </span>14<span
style="mso-spacerun: yes"> </span>15</span></p>
<p class=MsoNormal style='margin-left:21.0pt;text-indent:-21.0pt;mso-list:l3 level1 lfo2;
tab-stops:list 21.0pt'><span lang=EN-US style='font-family:
Wingdings'>l<span style='font:7.0pt "Times New Roman"'>
</span></span> <span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>函数</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>input</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>能输入一个字符串</span><span lang=EN-US>: <span style='color:blue'>x=input('
Enter anything > ',' s ') </span></span><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>。这里，在函数</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>input</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>里的附加参量</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US>’s’</span></b><span style='font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"'>告诉</span><span
lang=EN-US>MATLAB</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>，作为一个字符串，只要把用户输入传送到输出变量，就不需要引号。事实上，如果将引号包括进去，它们就变成返回字符串的一部分。</span></p>
<p class=MsoNormal style='margin-left:21.0pt;text-indent:-21.0pt;mso-list:l2 level1 lfo1;
tab-stops:list 21.0pt'><span lang=EN-US style='font-family:
Wingdings'>l<span style='font:7.0pt "Times New Roman"'>
</span></span> <span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>无论</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>fprintf</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>还是</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>sprintf</span></b><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>以同样方式处理输入参量，但</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>fprintf</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>把输出送到显示屏或文件中，而</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>sprintf</span></b><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>把输出返回到一个字符串中。</span></p>
<p class=MsoNormal style='margin-left:21.0pt;text-indent:-21.0pt;mso-list:l2 level1 lfo1;
tab-stops:list 21.0pt'> <span lang=EN-US style='font-family:
Wingdings'>l<span style='font:7.0pt "Times New Roman"'>
</span></span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>函数</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>feval</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>与</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>eval</span></b><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>类似，但在用法上有更多的限制。</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>feval('
fun ',x)</span></b><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>求由字符串</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>' fun '</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>给定的函数值，其输入参量是变量</span><span lang=EN-US>x</span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>。即</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>feval(' fun ',x)</span></b><span style='font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>等价于求</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>fun(x)</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>值。函数</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US style='color:red'>eval</span></b><span style='font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>，</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US style='color:red'>feval</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>的基本用途限在用户创建的函数内。一般地，</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>feval</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>可求出有大量输入参量的函数值，例如，</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>feval(' fun ', x, y, z)</span></b><span
lang=EN-US> </span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>等价于求</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US style='color:red'>fun(x, y, z)</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>值。</span></p>
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