实例 C语言Printf格式

ゞ浴缸里的玫瑰 2022-03-19 11:59 218阅读 0赞

使用printf打印时发现，如果数据类型和打印使用的类型不一致，结果就是混乱的。

这是因为printf本身并不进行数据的类型转换，他只是把输入按照给定的数据格式输出，如果二者不匹配，那么由于不同数据类型的二进制存储方式不一样，读出的数据就是错误的。

所以，为求稳妥，在使用printf，fprintf，scanf，fscanf在类型不一致时还是手动转化吧！

printf("%f\\n",1.3);

printf("%d %f\\n",1.3,1.3);

打印结果：

1.300000

\-858993459 -92559653408872784000000000000000000000000000000000000000000000.000000

前一行打印正确，但是后一行1.3与%d不匹配打印错误，不仅如此还影响到后一个也打印错误。

读入fscanf 用%f 读入赋给float型，要读入赋给double型，用%lf

C语言Printf格式

<table style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(192,192,192); border-right-color:rgb(192,192,192); border-bottom-color:rgb(192,192,192); border-left-color:rgb(192,192,192); border-collapse:collapse; color:rgb(0,0,0); font-family:Verdana,Arial,Helvetica,sans-serif; font-size:14px; line-height:25px"> 
 <tbody> 
  <tr> 
   <td style="border-top-width:1px; border-right-width:1px; border-bottom-width:1px; border-left-width:1px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-left-style:solid; border-top-color:rgb(192,192,192); border-right-color:rgb(192,192,192); border-bottom-color:rgb(192,192,192); border-left-color:rgb(192,192,192); border-collapse:collapse; padding-top:3px; padding-right:3px; padding-bottom:3px; padding-left:3px; word-break:normal!important"> 
    <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
     <span style="color:rgb(51,51,153)">C中格式字符串的一般形式为： %[标志][输出最小宽度][.精度][长度]类型， 其中方括号[]中的项为可选项。各项的意义介绍如下：</span> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(128,0,128)">1.类型类型字符用以表示输出数据的类型，其格式符和意义下表所示：</span> 
      <br> 
      <span style="color:rgb(0,0,128)">表示输出类型的格式字符</span>&nbsp;　　　　　&nbsp; 
      <span style="color:rgb(0,0,128)">格式字符意义</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       a&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 浮点数、十六进制数字和p-计数法(C99) 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       A&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 浮点数、十六进制数字和p-计数法(C99) 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       c 　　　　　　　　　　　　　　　　输出单个字符 
      <br> d 　　　　　　　　　　　　　　　　以十进制形式输出带符号整数(正数不输出符号) 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       e 　　　　　　　　　　　　　　　　以指数形式输出单、双精度实数 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       E 　　　　　　　　　　　　　　　　以指数形式输出单、双精度实数 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       f 　　　　　　　　　　　　　　　　 以小数形式输出单、双精度实数 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       g 　　　　　　　　　　　　　　　　以%f%e中较短的输出宽度输出单、双精度实数,%e格式在指数小于-4或者大&nbsp;&nbsp; 于等于精度时使用 
      <br> G 　　　　　　　　　　　　　　　　以%f%e中较短的输出宽度输出单、双精度实数,%e格式在指数小于-4或者大于等于精度时使用 
      <br> i&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 有符号十进制整数(与%d相同) 
      <br> o 　　　　　　　　　　　　　　　　以八进制形式输出无符号整数(不输出前缀O) 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       p&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 指针 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       s 　　　　　　　　　　　　　　　　输出字符串 
      <br> x 　　　　　　　　　　　　　　　　以十六进制形式输出无符号整数(不输出前缀OX) 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       X　　　　　　　　　　　　　　　　以十六进制形式输出无符号整数(不输出前缀OX) 
      <br> u 　　　　　　　　　　　　　　　　以十进制形式输出无符号整数 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       /*&nbsp;&nbsp; 测试常见的输出类型&nbsp;&nbsp; */ 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       #include "stdio.h" 
      <br> #include "conio.h" 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       main() 
      <br> { 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("The program test print style!\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以十进制形式输出带符号整数(正数不输出符号)&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%d\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%d\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以八进制形式输出无符号整数(不输出前缀O)&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%o\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%o\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以十六进制形式输出无符号整数(不输出前缀OX)&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%x\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%x\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以十进制形式输出无符号整数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%u\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%u\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以小数形式输出单、双精度实数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%f\n" , 223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%f\n" , 232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%f\n" , -223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%f\n" , -232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以指数形式输出单、双精度实数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%e\n" , 223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%e\n" , 232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%e\n" , -223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%e\n" , -232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以%f%e中较短的输出宽度输出单、双精度实数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%g\n" , 223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%g\n" , 232.111111111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%g\n" , -223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%g\n" , -232.111111111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 输出单个字符&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%c\n" , 'a'); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%c\n" , 97); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 输出单个字符&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%s\n" , "this is a test!"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%s\n" , "2342o34uo23u"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
      <br> } 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(128,0,128)">2.标志</span> 
      <br> 
      <span style="color:rgb(0,0,128)">标志字符为-、+、#、空格和0五种，其意义下表所示：<br> 标志格式字符 　　　　　标 志 意 义</span> 
      <br> - 　　　　　　　　　 结果左对齐，右边填空格 
      <br> + 　　　　　　　　　 输出符号(正号或负号) 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       空格&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 输出值为正时冠以空格，为负时冠以负号 
      <br> # 　　　　　　　　　对c，s，d，u类无影响；对o类，在输出时加前缀0；对x类， 
      <br> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 在输出时加前缀0x或者0X；对g，G 类防止尾随0被删除； 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 对于所有的浮点形式，#保证了即使不跟任何数字，也打印一个小数点字符 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 对于所有的数字格式，用前导0填充字段宽度，若出现-标志或者指定了精度(对于整数),忽略 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(128,0,128)">3.输出最小宽度</span> 
      <br> 
      <span style="color:rgb(0,0,128)">用十进制整数来表示输出的最少位数。若实际位数多于定义的宽度，则按实际位数输出，若实际位数少于定义的宽度则补以空格或0。</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       /*&nbsp;&nbsp; 测试标志字符为-、+、#、空格四种&nbsp;&nbsp; */ 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       #include "stdio.h" 
      <br> #include "conio.h" 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       main() 
      <br> { 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以十进制形式输出带符号整数(正数不输出符号)&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%-10d*\n", 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%+10d*\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%2d*\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%#d*\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(128,0,128)">&nbsp;&nbsp;&nbsp;</span>&nbsp;/*&nbsp;&nbsp; 以八进制形式输出无符号整数(不输出前缀O)&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%-10o*\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%+10o*\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%o*\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("*%#o*\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以十六进制形式输出无符号整数(不输出前缀OX)&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("$%-10x$\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("$%010x$\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("$% x$\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("$%#x$\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以十进制形式输出无符号整数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%-10u\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%+10u\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("% u\n" , 223); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%#u\n" , -232); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以小数形式输出单、双精度实数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%-10f\n" , 223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%+10f\n" , 232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("% f\n" , -223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%#f\n" , -232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以指数形式输出单、双精度实数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%-10e\n" , 223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%+10e\n" , 232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("% e\n" , -223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%#e\n" , -232.11111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 以%f%e中较短的输出宽度输出单、双精度实数&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%-10g\n" , 223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%+10g\n" , 232.111111111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("% g\n" , -223.11); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%#g\n" , -232.111111111111); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 输出单个字符&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%-10c\n" , 'a'); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%+10c\n" , 97); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("% c\n" , 'a'); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%#c\n" , 97); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; /*&nbsp;&nbsp; 输出单个字符&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%-20s\n" , "this is a test!"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%+20s\n" , "2342o34uo23u"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("% 20s\n" , "this is a test!");/* 不足补空格 */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%#s\n" , "2342o34uo23u"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("\n"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       } 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp; 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(128,0,128)">4.精度</span> 
      <br> 
      <span style="color:rgb(0,0,128)">精度格式符以“.”开头，后跟十进制整数。本项的意义是：如果输出数字，则表示小数的位数；如果输出的是字符，则表示输出字符的个数；若实际位数大于所定义的精度数，则截去超过的部分。</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       /*&nbsp;&nbsp; 测试精度&nbsp;&nbsp; */ 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       #include "stdio.h" 
      <br> #include "conio.h" 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       main() 
      <br> { 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("%.3d\n" , 5555); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; printf("%.3f\n" , 0.88888); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; printf("%.3f\n" , 0.9999); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp;&nbsp;&nbsp;&nbsp; printf("%.4s\n" , "this is a test!"); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
      <br> } 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(128,0,128)">5.长度</span> 
      <br> 
      <span style="color:rgb(0,0,128)">长度格式符为h,l两种，h表示按短整型量输出，l表示按长整型量输出。</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; h和整数转换说明符一起使用，表示一个short&nbsp;&nbsp; int 或者unsigned short int</span> 
      <span style="color:rgb(0,0,128)">类型的数值 ，示例：</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">%hu，%hx，%6.4hd</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; hh和整数转换说明符一起使用，表示一个short&nbsp;&nbsp; int 或者unsigned short类型的数值 ，示例：</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">%hhu，%hhx，%6.4hhd</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; j和整数转换说明符一起使用，表示一个intmax_t或者uintmax_t类型的数值 ，示例：</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">%jd,%8jx</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; l和整数转换说明符一起使用，表示一个long</span>&nbsp; 
      <span style="color:rgb(0,0,128)">int 或者unsigned long int类型的数值 ，示例：</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">%ld,%8lu</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; ll和整数转换说明符一起使用，表示一个long&nbsp;int 或者unsigned long int类型的数值 (C99)，示例：</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">%lld,%8llu</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; L和浮点转换说明符一起使用，表示一个long double的值，示例：%Lf，%10.4Le</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; t和整数转换说明符一起使用，表示一个ptrdiff_t值(两个指针之间的差相对应的类型)(C99)，示例：</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">%td,%12ti</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8"> 
      <span style="color:rgb(0,0,128)">&nbsp;&nbsp;&nbsp;&nbsp; z和整数转换说明符一起使用，表示一个size_t值(sizeof返回的类型)(C99)，示例：%zd,%12zx</span> 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       main(){ 
      <br> int a=15; 
      <br> float b=138.3576278; 
      <br> double c=35648256.3645687; 
      <br> char d='p'; 
      <br> printf("a=%d,%5d,%o,%x\n",a,a,a,a); 
      <br> printf("b=%f,%lf,%5.4lf,%e\n",b,b,b,b); 
      <br> printf("c=%lf,%f,%8.4lf\n",c,c,c); 
      <br> printf("d=%c,%8c\n",d,d); 
      <br> } 
      <br> a&lt;--15 
      <br> b&lt;--138.3576278 
      <br> c&lt;--35648256.3645687 
      <br> d&lt;--'p' 
      <br> 
      <br> main() 
      <br> { 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; int a=29; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; float b=1243.2341; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; double c=24212345.24232; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; char d='h'; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("a=%d,%5d,%o,%x\n",a,a,a,a); 
      <br> &nbsp;&nbsp;&nbsp; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; /* 其中“%f”和“%lf ”格式的输出相同，说明“l”符对“f”类型无影响 
      <br> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; * “%5.4lf”指定输出宽度为5，精度为4，由于实际长度超过5故应该按实际位数输出，小数位数超过4位&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *&nbsp;&nbsp; 部分被截去 
      <br> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("b=%f,%lf,%5.4lf,%e\n",b,b,b,b); 
      <br> &nbsp;&nbsp;&nbsp; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; /* 输出双精度实数，“%8.4lf ”由于指定精度为4位故截去了超过4位的部分 */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("c=%lf,%f,%8.4lf\n",c,c,c); 
      <br> &nbsp;&nbsp;&nbsp; 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; /* 输出字符量d，其中“%8c ”指定输出宽度为8故在输出字符p之前补加7个空格 */ 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; printf("d=%c,%8c\n",d,d); 
      <br> &nbsp;&nbsp;&nbsp;&nbsp; getch(); 
      <br> } 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp; 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       使用printf函数时还要注意一个问题，那就是输出表列中的求值顺序。不同的编译系统不一定相同，可以从左到右，也可从右到左。Turbo C是按从右到左进行的 
      <br> main(){ 
      <br> int i=8; 
      <br> printf("%d\n%d\n%d\n%d\n%d\n",++i,--i,i--,i++,-i--); 
      <br> } 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp; 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       6.特殊用法 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       &nbsp; 
     </div> 
     <div style="margin-top:0px; margin-right:0px; margin-bottom:0px; margin-left:0px; line-height:1.8">
       对于m.n的格式还可以用如下方法表示（例） 
      <br> char ch[20]; 
      <br> printf("%*.*s\n",m,n,ch); 
      <br> 前边的*定义的是总的宽度，后边的定义的是输出的个数。分别对应外面的参数m和n 。我想这种方法的好处是可以在语句之外对参数m和n赋值，从而控制输出格式。 
      <br> 今天(06.6.9)又看到一种输出格式 %n 可以将所输出字符串的长度值赋绐一个变量, 见下例: 
      <br> 
      <br> int slen; 
      <br> 
      <br> printf("hello world%n", &amp;slen); 
      <br> 
      <br> 执行后变量被赋值为11。 
      <br> 
      <br> 又查了一下, 看到一篇文章( 
      <a href="http://www.eefocus.com/blog/link2url.php?link=http%3A%2F%2Fwww.programfan.com%2Farticle%2Fshowarticle.asp%3Fid%3D2968" style="color:rgb(169,23,24); text-decoration:none" rel="nofollow">查看</a>)说这种格式输出已经确认为一个安全隐患，并且已禁用。再搜搜果然这种用法都被用来搞什么溢出、漏洞之类的，随便找了一个： 
      <a href="http://www.eefocus.com/blog/link2url.php?link=http%3A%2F%2Fdiliangliang.blogdriver.com%2Fdiliangliang%2F979462.html" style="color:rgb(169,23,24); text-decoration:none" rel="nofollow">格式化字符串攻击笔记</a> 
      <br> 
      <br> 特别注意下%*.*s这种用法 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>