Node.js Buffer.writeUIntBE()方法
原文:https://www . geesforgeks . org/node-js-buffer-writeuintbe-method/
Buffer.writeUIntBE() 方法用于使用大端格式将指定的字节写入 Buffer 对象。它支持高达 6 字节的精度。当使用非无符号整数的值时，其行为是未定义的。
语法:
Buffer.writeUIntBE( value, offset, byteLength )
参数:该方法接受三个参数，如上所述，如下所述:
- Value: Specifies the number to be written into the Buffer object.
- Offset: Specify the number of bytes to skip before writing to the buffer. The value of offset lies in 0 < = offset < = buf.length–byte length .
- Byte Length: Specifies the number of bytes written into the buffer. The value of the byte length is 0 < The byte length < = 6 .
返回值:返回偏移量加上写入的字节数。
下面的例子说明了在 Node.js 中使用 Buffer.writeUIntBE()方法:
例 1:
// Node.js program to demonstrate the
// Buffer.writeUIntBE() method
// Creating a buffer of size 4
const buffer_1 = Buffer.allocUnsafe(4);
// Writes byteLength bytes of value to buf
// at the specified offset.
buffer_1.writeUIntBE(0x13141516, 0, 4);
// Display the result
console.log(buffer_1);
// Creating a buffer of size 6
const buffer_2 = Buffer.allocUnsafe(6);
buffer_2.writeUIntBE(0x131314141515, 0, 6);
// Display the result
console.log(buffer_2);
输出:
<Buffer 13 14 15 16>
<Buffer 13 13 14 14 15 15>
例 2:
// Node.js program to demonstrate the
// Buffer.writeUIntBE() method
// Creating a buffer of given size
const buffer = Buffer.allocUnsafe(8);
//Before writing anything
console.log("Before filling buffer");
console.log(buffer);
// To fill first 6 bytes, take offset 0
// and bytelength 6
console.log("After filling 6 bytes");
buffer.writeUIntBE(0xaa1313147586, 0, 6);
console.log(buffer);
// To fill next 2 bytes add 6 offet
// and bytelength 2
console.log("After filling next 2 bytes");
buffer.writeUIntBE(0x0123, 6, 2)
console.log(buffer);
输出:
Before filling buffer
<Buffer 00 00 00 00 00 00 00 00>
After filling 6 bytes
<Buffer aa 13 13 14 75 86 00 00>
After filling next 2 bytes
<Buffer aa 13 13 14 75 86 01 23>
注意:以上程序使用node index.js命令编译运行。
参考:https://nodejs . org/API/buffer . html # buff _ writeuintbe _ value _ offset _ byte length
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