Node.js Buffer.copy()方法
原文:https://www.geeksforgeeks.org/node-js-buffer-copy-method/
缓冲区是一个临时存储器，当数据从一个地方移动到另一个地方时，它存储数据。它就像一个整数数组。
Buffer.copy()方法只需将所有值从输入缓冲区复制到另一个缓冲区。
语法:
buffer.copy( target, targetStart, sourceStart, sourceEnd )
参数:这个方法接受两个参数，如上所述，如下所述:
- Target: It is a buffer where all values need to be copied.
- Targetstart: refers to the starting index at which the elements of the target buffer start writing. Its default value is 0.
- Source start: is the index of the input buffer from which the value is copied. Its default value is 0.
- sourceend: The index of the input buffer where the value copy will be completed. Its default value is buffer.lengthsize.
返回值:该方法返回指示复制字节数的数字。
注意:从输入缓冲区复制值，并将其覆盖到输出缓冲区，即使目标内存区域(索引)已经存在。即使目标内存区域与输入缓冲区重叠，也将数据从输入缓冲区的一个区域复制到目标缓冲区的一个区域。
下面的例子说明了 Buffer.includes()方法在 Node.js 中的使用:
例 1:
// Node.js program to demonstrate the
// Buffer.copy() Method
// Creating a buffer
var buffer2 = Buffer.from('for');
var buffer1 = Buffer.from('GeeksandGeeks');
buffer2.copy(buffer1, 5, 0);
console.log(buffer1.toString());
输出:
GeeksforGeeks
例 2:
// Node.js program to demonstrate the
// Buffer.copy() Method
var buffer2 = Buffer.allocUnsafe(5);
var buffer1 = Buffer.from('Geeks');
for (let i = 0; i < 5; i++) {
// Adds: 'a b c d e' as 97 98 99 100 101
// are their respective ASCII values
buffer2[i] = i + 97;
}
buffer2.copy(buffer1, 2);
// Prints 'Geabc' as the input buffer1
// carries 'Geeks' and we provided the
// targetStart index as 2
// so elements will replace the values in
// buffer1 starting from index 2
console.log(buffer1.toString());
输出:
Geabc
注意:以上程序使用node index.js命令编译运行。
参考:T2【https://nodejs . org/API/buffer . html # buffer _ buf _ copy _ target start _ source start _ source end
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