46.数字到字符串的转换

• double类型转换到char*

      char buffer[128];
      double value = 12.2345678;
  3     _gcvt(value, 5, buffer);//5有效数字
      printf("%s", buffer);

• unsigned int类型转换到char*

      unsigned int num = 32;
      char str[32] = { 0 };
      //以2进制方式转换
   4     _ultoa(num, str, 2);
      printf("%s
  ", str);
  
      //以8进制方式转换
      _ultoa(num, str, 8);
      printf("%s
  ", str);
  
      //以10进制方式转换
      _ultoa(num, str, 10);
      printf("%s
  ", str);
      //以16进制方式转换
      _ultoa(num, str, 16);
      printf("%s
  ", str);

• int类型转换到char*

      int num = -32;
      char str[32] = { 0 };
   3     _ltoa(num, str, 2);
      printf("%s
  ", str);
  
      _ltoa(num, str, 8);
      printf("%s
  ", str);
      _ltoa(num, str, 10);
      printf("%s
  ", str);
      _ltoa(num, str, 16);
      printf("%s
  ", str);

• 获取double类型的数据信息(1)

          double data = 12345.4567;
      
      int decimal;//整数的位数
      int sign;//1代表负，0代表证
      int precision = 9;//数字的宽度，强行指定
      char *buffer;//指针
  
      //把double类型转化为char*
      buffer = _ecvt(data, precision, &decimal, &sign);//自动分配内存
      printf("buffer=%s
  ", buffer);
      printf("sign=%d
  ", sign);
      printf("decimal=%d
  ", decimal);
      printf("precision =%d
  ", precision);    

   

• 获取double类型的数据信息(2)

      double data = 12345.4567;
  
      int decimal;//整数的位数
      int sign;//1代表负，0代表证
      int precision = 4;//小数点后的精度
      char *buffer;//指针
  
      buffer=_fcvt(data, precision, &decimal, &sign);
      printf("buffer=%s
  ", buffer);
      printf("sign=%d
  ", sign);
      printf("decimal=%d
  ", decimal);
      printf("precision =%d
  ", precision);