Node.js Buffer.readUInt16BE()方法
原文:https://www . geesforgeks . org/node-js-buffer-readuint 16 be-method/
Buffer.readUInt16BE()方法是 Buffer 模块中类 Buffer 的内置应用编程接口，用于从指定偏移量处分配的缓冲区中读取 16 位值。
语法:
Buffer.readUInt16BE( offset )
参数:该方法接受单参数偏移量，该偏移量指定读取前要跳过的字节数，或者简单地表示缓冲区中的索引。缓冲值位于 0 < =偏移< =缓冲长度–2。其默认值为 0。
返回值:这个方法返回一个无符号的 16 位整数值，它是从缓冲区以大端格式读取的(Buffer.readUInt16LE()以小端格式读取 16 位)。
下面的例子说明了在 Node.js 中使用 Buffer.readUInt16BE()方法:
例 1:
// Node.js program to demonstrate the
// Buffer.readUInt16BE() method
// Allocating buffer from array
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]);
// Printing allocated buffer
console.log(buf);
// Reading 16bits data from the buffer
// and printing it as a string
console.log(buf.readUInt16BE(0).toString(16));
console.log(buf.readUInt16BE(1).toString(16));
console.log(buf.readUInt16BE(2).toString(16));
输出:
<Buffer 21 09 19 98>
2109
919
1998
例 2:
// Node.js program to demonstrate the
// Buffer.readUInt16BE() method
// Allocating buffer from array
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]);
// Printing allocated buffer
console.log(buf);
// Reading 16bits data from the buffer
// and printing it as a string
console.log(buf.readUInt16BE(0).toString(16));
console.log(buf.readUInt16LE(0).toString(16));
console.log(buf.readUInt16BE(1).toString(16));
console.log(buf.readUInt16LE(1).toString(16));
console.log(buf.readUInt16BE(2).toString(16));
console.log(buf.readUInt16LE(2).toString(16));
输出:
<Buffer 21 09 19 98>
2109
921
919
1909
1998
9819
例 3:
// Node.js program to demonstrate the
// Buffer.readUInt16BE() method
// Allocating buffer from array
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]);
// Printing allocated buffer
console.log(buf);
// Reading 16bits data from the buffer
// and printing it as a string
console.log(buf.readUInt16BE(0).toString(16));
console.log(buf.readUInt16BE(1).toString(16));
console.log(buf.readUInt16BE(2).toString(16));
// Wrong index is provided to produce error
console.log(buf.readUInt16BE(3).toString(16));
输出:
<Buffer 21 09 19 98>
2109
919
1998
internal/buffer.js:49
throw new ERR_OUT_OF_RANGE(type || 'offset',
^
RangeError [ERR_OUT_OF_RANGE]: The value of "offset" is out of range.
It must be >= 0 and <= 2\. Received 3
at boundsError (internal/buffer.js:49:9)
at Buffer.readUInt16BE (internal/buffer.js:215:5)
. . .
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 # buffer _ buf _ readuint 16 be _ offset
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