http://aminiam.com/tags/i/o/Recent content in I/O on Aminiam's BlogHugo -- gohugo.ioen-usWed, 02 Sep 2026 13:59:38 +0800http://aminiam.com/p/printf-scanf-format/Wed, 02 Sep 2026 13:59:38 +0800http://aminiam.com/p/printf-scanf-format/<h2 id="一格式说明符">一、格式说明符 </h2><table> <thead> <tr> <th>格式符</th> <th>printf 参数类型</th> <th>scanf 参数类型</th> <th>说明</th> </tr> </thead> <tbody> <tr> <td><code>%d</code></td> <td><code>int</code></td> <td><code>int*</code></td> <td>十进制有符号整数</td> </tr> <tr> <td><code>%u</code></td> <td><code>unsigned int</code></td> <td><code>unsigned int*</code></td> <td>十进制无符号整数</td> </tr> <tr> <td><code>%o</code></td> <td><code>unsigned int</code></td> <td><code>unsigned int*</code></td> <td>八进制</td> </tr> <tr> <td><code>%x</code></td> <td><code>unsigned int</code></td> <td><code>unsigned int*</code></td> <td>十六进制（小写）</td> </tr> <tr> <td><code>%X</code></td> <td><code>unsigned int</code></td> <td><code>unsigned int*</code></td> <td>十六进制（大写）</td> </tr> <tr> <td><code>%f</code></td> <td><code>double</code></td> <td><code>float*</code></td> <td>浮点数（printf 用 <code>%f</code>/<code>%lf</code> 均可，scanf 必须 <code>%f</code> 给 float，<code>%lf</code> 给 double）</td> </tr> <tr> <td><code>%e</code></td> <td><code>double</code></td> <td><code>float*</code></td> <td>科学计数法（小写 e）</td> </tr> <tr> <td><code>%g</code></td> <td><code>double</code></td> <td><code>float*</code></td> <td>自动选 <code>%f</code> 或 <code>%e</code>（较短）</td> </tr> <tr> <td><code>%c</code></td> <td><code>char</code></td> <td><code>char*</code></td> <td>单个字符</td> </tr> <tr> <td><code>%s</code></td> <td><code>const char*</code></td> <td><code>char[]</code></td> <td>字符串（遇空白停止）</td> </tr> <tr> <td><code>%p</code></td> <td><code>const void*</code></td> <td><code>void**</code></td> <td>指针地址（十六进制）</td> </tr> <tr> <td><code>%n</code></td> <td><code>int*</code></td> <td><code>int*</code></td> <td>写入已输出/读取的字符数</td> </tr> <tr> <td><code>%%</code></td> <td>-</td> <td>-</td> <td>输出字面量 <code>%</code></td> </tr> </tbody> </table> <h2 id="二长度修饰符">二、长度修饰符 </h2><table> <thead> <tr> <th>修饰符</th> <th>适用类型示例</th> <th>格式</th> </tr> </thead> <tbody> <tr> <td><code>hh</code></td> <td><code>signed char</code> / <code>unsigned char</code></td> <td><code>%hhd</code>, <code>%hhu</code></td> </tr> <tr> <td><code>h</code></td> <td><code>short</code> / <code>unsigned short</code></td> <td><code>%hd</code>, <code>%hu</code></td> </tr> <tr> <td><code>l</code></td> <td><code>long</code> / <code>unsigned long</code></td> <td><code>%ld</code>, <code>%lu</code></td> </tr> <tr> <td><code>ll</code></td> <td><code>long long</code> / <code>unsigned long long</code></td> <td><code>%lld</code>, <code>%llu</code></td> </tr> <tr> <td><code>L</code></td> <td><code>long double</code></td> <td><code>%Lf</code>, <code>%Le</code></td> </tr> <tr> <td><code>z</code></td> <td><code>size_t</code></td> <td><code>%zd</code></td> </tr> <tr> <td><code>t</code></td> <td><code>ptrdiff_t</code></td> <td><code>%td</code></td> </tr> </tbody> </table> <h2 id="三printf常用标志">三、<code>printf</code>常用标志 </h2><table> <thead> <tr> <th>标志</th> <th>作用</th> <th>示例（<code>%</code>后加标志）</th> </tr> </thead> <tbody> <tr> <td><code>-</code></td> <td>左对齐（默认右对齐）</td> <td><code>%-10d</code></td> </tr> <tr> <td><code>+</code></td> <td>强制显示正负号</td> <td><code>%+d</code></td> </tr> <tr> <td>空格</td> <td>正数前加空格</td> <td><code>% d</code></td> </tr> <tr> <td><code>#</code></td> <td>八进制前加<code>0</code>，十六进制加<code>0x</code>/<code>0X</code>，浮点数强制小数点</td> <td><code>%#o</code>, <code>%#x</code>, <code>%#f</code></td> </tr> <tr> <td><code>0</code></td> <td>用 <code>0</code> 填充宽度（而非空格）</td> <td><code>%08d</code></td> </tr> </tbody> </table> <h2 id="四宽度与精度">四、宽度与精度 </h2><table> <thead> <tr> <th>格式</th> <th>含义</th> <th>示例</th> </tr> </thead> <tbody> <tr> <td><code>%最小宽度d</code></td> <td>输出至少占 n 位，不足补空格</td> <td><code>%5d</code></td> </tr> <tr> <td><code>%.精度f</code></td> <td>小数位数（浮点）/ 最大字符数（字符串）/ 最少数字位数（整数）</td> <td><code>%.2f</code>, <code>%.5s</code></td> </tr> <tr> <td><code>%*.*f</code></td> <td>宽度和精度由参数提供</td> <td><code>printf(&quot;%*.*f&quot;, w, p, val);</code></td> </tr> </tbody> </table> <h2 id="五scanf-特殊用法">五、scanf 特殊用法 </h2><table> <thead> <tr> <th>用法</th> <th>说明</th> <th>示例</th> </tr> </thead> <tbody> <tr> <td><code>*</code></td> <td>抑制赋值（跳过）</td> <td><code>scanf(&quot;%*d %d&quot;, &amp;n);</code></td> </tr> <tr> <td><code>[集合]</code></td> <td>只读指定字符集</td> <td><code>%[a-z]</code>（读小写字母）</td> </tr> <tr> <td><code>[^]</code></td> <td>读直到遇到某字符</td> <td><code>%[^,]</code>（读逗号前）</td> </tr> </tbody> </table>