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Node.js | Buffer.writeDoubleBE() Method

  • Last Updated : 31 Dec, 2019

The Buffer.writeDoubleBE() method is an inbuilt application programming interface of class Buffer within the Buffer module which is used to writes big endian 64-bits double value to an allocated buffer at the specified offset.

Syntax:

Buffer.writeDoubleBE( value, offset )

Parameters: This method accept two parameters as mentioned above and described below:

  • value: This parameter specifies 4 bytes floating point value to be written to the buffer. It should be a valid 64 bits big endian double value. Behavior is undefined when value is anything other than this.
  • offset: It specifies the number of bytes to skip before write or simply signify the index in the buffer. The value of offset lies 0 <= offset <= Buffer.length – 8. Its default value is 0.

Return Value: This method returns an integer value that is the sum of offset and number of bytes written.

Below examples illustrate the use of Buffer.writeDoubleBE() method in Node.js:



Example 1:




// Node.js program to demonstrate the 
// Buffer.writeDoubleBE() method 
       
// Allocating 32 bytes buffer
const buf = Buffer.allocUnsafe(32);
  
// Writing 64bits or 8 bytes double values
// to the buffer and printing returned
//  value to console
console.log(buf.writeDoubleBE(123.123, 0));
console.log(buf.writeDoubleBE(166.089, 8));
console.log(buf.writeDoubleBE(231.678, 16));
console.log(buf.writeDoubleBE(341.781, 24));
   
// Display the buffer
console.log(buf);

Output:

8
16
24
32
<Buffer 40 5e c7 df 3b 64 5a 1d 40 64 c2 d9 16 87 2b
02 40 6c f5 b2 2d 0e 56 04 40 75 5c 7e f9 db 22 d1>

Example 2:




// Node.js program to demonstrate the 
// Buffer.writeDoubleBE() method 
       
// Allocating 16 bytes buffer
const buf = Buffer.allocUnsafe(16);
  
// Printing buffer before writing value
console.log("Before writing into buffer:");
console.log(buf);
   
// Writing 64 bits or 8 bytes double values
// to the buffer and printing returned
// value to console
console.log(buf.writeDoubleBE(219.098, 0));
console.log(buf.writeFloatBE(169.096, 8));
   
// Printing the buffer after writing into buffer
console.log("After writing into buffer:");
console.log(buf);

Output:

Before writing into buffer:
<Buffer f8 02 ff bc f8 01 00 00 f8 02 ff bc f8 01 00 00>
8
12
After writing into buffer:
<Buffer 40 6b 63 22 d0 e5 60 42 43 29 18 93 f8 01 00 00>

Note: The above program will compile and run by using the node index.js command.

Reference: https://nodejs.org/api/buffer.html#buffer_buf_writedoublebe_value_offset




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