接受含有大写和小写字母的字符串，返回这个字符串的全代码,C代码库,德仔网

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【C】接受含有大写和小写字母的字符串，返回这个字符串的全
作者:Dezai.CN / 发布于2011/7/8/ 766
若要得到小写字母，找出大写字母并将其改为小写字母。若要得到大写字母则相反。
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<pre><div><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #000000">iostream</span><span style="color: #000000">></span><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #0000ff">string</span><span style="color: #000000">></span><span style="color: #000000"></span><span style="color: #0000ff">using</span><span style="color: #000000"> </span><span style="color: #0000ff">namespace</span><span style="color: #000000"> std;</span><span style="color: #0000ff">bool</span><span style="color: #000000"> tolower_or_toupper(</span><span style="color: #0000ff">string</span><span style="color: #000000"> </span><span style="color: #000000">&</span><span style="color: #000000">str, </span><span style="color: #0000ff">char</span><span style="color: #000000"> option){    </span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #800080">0</span><span style="color: #000000">;    </span><span style="color: #0000ff">if</span><span style="color: #000000"> (option </span><span style="color: #000000">!=</span><span style="color: #000000"> </span><span style="color: #800000">'</span><span style="color: #800000">l</span><span style="color: #800000">'</span><span style="color: #000000"> </span><span style="color: #000000">&&</span><span style="color: #000000"> option </span><span style="color: #000000">!=</span><span style="color: #000000"> </span><span style="color: #800000">'</span><span style="color: #800000">u</span><span style="color: #800000">'</span><span style="color: #000000">) //使用字符'l'和'u'判断是转换为小写还是大写字母    {        cout </span><span style="color: #000000"><<</span><span style="color: #000000"> option </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;        cout </span><span style="color: #000000"><<</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">The option is error! It must be 'l' or 'u'</span><span style="color: #800000">"</span><span style="color: #000000"> </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;        </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #0000ff">false</span><span style="color: #000000">;    }    </span><span style="color: #0000ff">for</span><span style="color: #000000"> (i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #800080">0</span><span style="color: #000000">; i</span><span style="color: #000000"><</span><span style="color: #000000">str.length();i</span><span style="color: #000000">++</span><span style="color: #000000">)    {        </span><span style="color: #0000ff">if</span><span style="color: #000000"> (isupper(str.at(i)) </span><span style="color: #000000">&&</span><span style="color: #000000"> option </span><span style="color: #000000">==</span><span style="color: #000000"> </span><span style="color: #800000">'</span><span style="color: #800000">l</span><span style="color: #800000">'</span><span style="color: #000000">)//转换为小写的        {            str.at(i) </span><span style="color: #000000">=</span><span style="color: #000000"> str.at(i) </span><span style="color: #000000">+</span><span style="color: #000000"> </span><span style="color: #800000">'</span><span style="color: #800000">a</span><span style="color: #800000">'</span><span style="color: #000000">-</span><span style="color: #800000">'</span><span style="color: #800000">A</span><span style="color: #800000">'</span><span style="color: #000000">;//ascii码记不住没关系，临时转换就是了        }        </span><span style="color: #0000ff">else</span><span style="color: #000000"> </span><span style="color: #0000ff">if</span><span style="color: #000000"> (islower(str.at(i)) </span><span style="color: #000000">&&</span><span style="color: #000000"> option </span><span style="color: #000000">==</span><span style="color: #000000"> </span><span style="color: #800000">'</span><span style="color: #800000">u</span><span style="color: #800000">'</span><span style="color: #000000">)//转换为大写的        {            str.at(i) </span><span style="color: #000000">=</span><span style="color: #000000"> str.at(i) </span><span style="color: #000000">+</span><span style="color: #000000"> </span><span style="color: #800000">'</span><span style="color: #800000">A</span><span style="color: #800000">'</span><span style="color: #000000">-</span><span style="color: #800000">'</span><span style="color: #800000">a</span><span style="color: #800000">'</span><span style="color: #000000">;        }    }    </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #0000ff">true</span><span style="color: #000000">;}</span></div></pre>
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下面是一个测试程序：
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<pre><div><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #000000">iostream</span><span style="color: #000000">></span><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #0000ff">string</span><span style="color: #000000">></span><span style="color: #000000"></span><span style="color: #0000ff">using</span><span style="color: #000000"> </span><span style="color: #0000ff">namespace</span><span style="color: #000000"> std;</span><span style="color: #0000ff">bool</span><span style="color: #000000"> tolower_or_toupper(</span><span style="color: #0000ff">string</span><span style="color: #000000"> </span><span style="color: #000000">&</span><span style="color: #000000">str, </span><span style="color: #0000ff">char</span><span style="color: #000000"> option);</span><span style="color: #0000ff">int</span><span style="color: #000000"> main(){    </span><span style="color: #0000ff">string</span><span style="color: #000000"> str </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">aFkFHkKFNDJHDNFkfksdjjek</span><span style="color: #800000">"</span><span style="color: #000000">;    tolower_or_toupper(str, </span><span style="color: #800000">'</span><span style="color: #800000">l</span><span style="color: #800000">'</span><span style="color: #000000">);//全部转换为小写的    cout </span><span style="color: #000000"><<</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">The loer letters is : </span><span style="color: #800000">"</span><span style="color: #000000"> </span><span style="color: #000000"><<</span><span style="color: #000000"> str </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;    tolower_or_toupper(str, </span><span style="color: #800000">'</span><span style="color: #800000">u</span><span style="color: #800000">'</span><span style="color: #000000">);//全部转换为大写的    cout </span><span style="color: #000000"><<</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">The upper letters is : </span><span style="color: #800000">"</span><span style="color: #000000"> </span><span style="color: #000000"><<</span><span style="color: #000000"> str </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;    </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #800080">1</span><span style="color: #000000">;}</span></div></pre>
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下面的也是一个测试程序，只不过嫁了个文件操作：

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<pre><div><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #000000">iostream</span><span style="color: #000000">></span><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #000000">fstream</span><span style="color: #000000">></span><span style="color: #000000">#include </span><span style="color: #000000"><</span><span style="color: #0000ff">string</span><span style="color: #000000">></span><span style="color: #000000"></span><span style="color: #0000ff">using</span><span style="color: #000000"> </span><span style="color: #0000ff">namespace</span><span style="color: #000000"> std;</span><span style="color: #0000ff">bool</span><span style="color: #000000"> tolower_or_toupper(</span><span style="color: #0000ff">string</span><span style="color: #000000"> </span><span style="color: #000000">&</span><span style="color: #000000">str, </span><span style="color: #0000ff">char</span><span style="color: #000000"> option);</span><span style="color: #0000ff">int</span><span style="color: #000000"> main(){    </span><span style="color: #0000ff">string</span><span style="color: #000000"> str </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">aFkFHkKFNDJHDNFkfksdjjek</span><span style="color: #800000">"</span><span style="color: #000000">;    tolower_or_toupper(str, </span><span style="color: #800000">'</span><span style="color: #800000">l</span><span style="color: #800000">'</span><span style="color: #000000">);    cout </span><span style="color: #000000"><<</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">The loer letters is : </span><span style="color: #800000">"</span><span style="color: #000000"> </span><span style="color: #000000"><<</span><span style="color: #000000"> str </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;    str </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">aFkFHkKFNDJHDNFkfksdjjek</span><span style="color: #800000">"</span><span style="color: #000000">;    tolower_or_toupper(str, </span><span style="color: #800000">'</span><span style="color: #800000">u</span><span style="color: #800000">'</span><span style="color: #000000">);    cout </span><span style="color: #000000"><<</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">The upper letters is : </span><span style="color: #800000">"</span><span style="color: #000000"> </span><span style="color: #000000"><<</span><span style="color: #000000"> str </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;        </span><span style="color: #008000">//</span><span style="color: #008000">测试一个文件的更改</span><span style="color: #008000"></span><span style="color: #000000">    </span><span style="color: #0000ff">char</span><span style="color: #000000"> buffer[</span><span style="color: #800080">256</span><span style="color: #000000">];    </span><span style="color: #0000ff">char</span><span style="color: #000000"> delim;    fstream file;    file.open(</span><span style="color: #800000">"</span><span style="color: #800000">tmp</span><span style="color: #800000">"</span><span style="color: #000000">);    </span><span style="color: #0000ff">if</span><span style="color: #000000"> (file.is_open())     {        file.</span><span style="color: #0000ff">get</span><span style="color: #000000">(buffer,</span><span style="color: #800080">256</span><span style="color: #000000">, delim</span><span style="color: #000000">=</span><span style="color: #000000">EOF);        cout </span><span style="color: #000000"><<</span><span style="color: #000000"> buffer </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;        file.close();    }    str.assign(buffer);    tolower_or_toupper(str, </span><span style="color: #800000">'</span><span style="color: #800000">u</span><span style="color: #800000">'</span><span style="color: #000000">);    cout </span><span style="color: #000000"><<</span><span style="color: #000000"> </span><span style="color: #800000">"</span><span style="color: #800000">The upper letters is : </span><span style="color: #800000">"</span><span style="color: #000000"> </span><span style="color: #000000"><<</span><span style="color: #000000"> str </span><span style="color: #000000"><<</span><span style="color: #000000"> endl;    </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #800080">1</span><span style="color: #000000">;}</span></div></pre>
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编译和运行：

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<pre><div><span style="color: #000000">[hanxi@hanxi-workstation Documents]$ g++ letter.cpp testletter.cpp -o strtest</span></div><div><span style="color: #000000">[hanxi@hanxi</span><span style="color: #000000">-</span><span style="color: #000000">workstation Documents]$ .</span><span style="color: #000000">/</span><span style="color: #000000">strtestThe loer letters </span><span style="color: #0000ff">is</span><span style="color: #000000"> : afkfhkkfndjhdnfkfksdjjekThe upper letters </span><span style="color: #0000ff">is</span><span style="color: #000000"> : AFKFHKKFNDJHDNFKFKSDJJEKWalter</span><span style="color: #800000">'</span><span style="color: #800000">s goal in life was to become a successful surgeon. First, though, he had to get through high school, so he concentrated all his efforts on his studies &mdash;&mdash; in particular, biology, chemistry, and math. Because he worked constantly on these subject</span><span style="color: #800000"></span><span style="color: #000000">The upper letters </span><span style="color: #0000ff">is</span><span style="color: #000000"> : WALTER</span><span style="color: #800000">'</span><span style="color: #800000">S GOAL IN LIFE WAS TO BECOME A SUCCESSFUL SURGEON. FIRST, THOUGH, HE HAD TO GET THROUGH HIGH SCHOOL, SO HE CONCENTRATED ALL HIS EFFORTS ON HIS STUDIES &mdash;&mdash; IN PARTICULAR, BIOLOGY, CHEMISTRY, AND MATH. BECAUSE HE WORKED CONSTANTLY ON THESE SUBJECT</span></div></pre>
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