TXT文件读写

亦凉 2023-01-18 09:11 76阅读 0赞

# 1.txt文件读 #

### json文件 ###

{
            "name": "mculover666",
            "age":  22,
            "weight":       55.5,
            "address":      {
                    "country":      "China",
                    "zip-code":     111111
            },
            "skill":        ["C", "Java", "Python"],
            "student":      false
    }

### ultraedit的16进制显示 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTc2MTE2_size_16_color_FFFFFF_t_70][]

### 读写程序  ###

#include <stdio.h>
    #include <stdlib.h>
    
    int main(void)
    {
      FILE *fp= NULL;
      unsigned int file_len;
      int num;
      char *p;
    	
      if( NULL == (fp = fopen("json.txt","r")))  
      {
        printf( "Problem opening the file\n" );
      }
    
      //得到文件的长度	
      fseek(fp,0,SEEK_END);
      file_len = ftell(fp);
    /* int fd;
       file_len  = lseek(fd,0,SEEK_END); */
      printf("the file len is %d\n",file_len);
    
      char *buff = (char*)malloc(file_len); 	
      fseek(fp,0,SEEK_SET);
    	
      fread(buff,sizeof(char),file_len, fp);
           
      buff[file_len] = '\0';//txt文件结束为}或者或者回车换行，需要加上字符串结尾标志0
      
      p = buff;
      for(num = 0 ;num < file_len+1 ;num++)//在linux中，此处file_len+2得到的最后一位虽然也是0，但是不严谨，必须使用buff[file_len] = '\0';语句加上字符串的结尾标志
      {
        printf("%2X ",*p);
        p++;
      }//{的ASCII码7B,}的ASCII码是7D,json文件结尾还有0D 0A(回车，换行)
      printf("\n%s\n",buff);
    
      fclose(fp);
      free(buff);
      return 0;
    }

### linux运行结果  ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTc2MTE2_size_16_color_FFFFFF_t_70 1][]

###  windows运行结果 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTc2MTE2_size_16_color_FFFFFF_t_70 2][]

### **注意：Windows和Linux存在换行的区别** ###

**疑问：Dos下换行应该是 \\r\\n（0D0A） ，Linux下应该是 \\n（0A） ，上述结果恰好相反？**

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTc2MTE2_size_16_color_FFFFFF_t_70]: /images/20221021/0f861c35d78f4a5db1257b86c04d09aa.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTc2MTE2_size_16_color_FFFFFF_t_70 1]: /images/20221021/66e36ee7bd9a409cb979bfb58f4fc1da.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTc2MTE2_size_16_color_FFFFFF_t_70 2]: /images/20221021/ad20620a889f41b7994b2de8f4ede9ca.png