javascript nodejs 中的 C scanf 等效项
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C scanf equivalent in nodejs
提问by Alexander T.
If I want to read from the input stream in CI write scanf., Is there equivalent method in NodeJSto do the same?
如果我想从C 中的输入流中读取我写的scanf.，NodeJS 中是否有等效的方法来做同样的事情？
For example, here's the code in C
例如，这里是C 中的代码
int n,
m,
i;
scanf("%d", &n);
for (i = 0; i < n; i++) {
scanf("%d", &m);
............
}
Here's where I'm starting from in Node... TODOindicates where I'm stuck:
这是我从 Node 开始的地方...... TODO表明我被卡住的地方：
process.stdin.resume();
process.stdin.setEncoding("ascii");
process.stdin.on("data", function (input) {
var n = +input;
for (var i = 0; i < n; i++) {
// TODO
}
});
回答by user7116
For starters, calling scanfand the dataevent for a readable stream in NodeJS are not equivalent. In the NodeJS example, you will need to parse the chunk of the input you've received.
对于初学者来说，NodeJS 中可读流的调用scanf和data事件并不等效。在 NodeJS 示例中，您需要解析收到的输入块。
You can examine how these chunks are sent to you by replacing the body of your on method with a simple:
您可以通过用简单的方法替换 on 方法的主体来检查这些块是如何发送给您的：
process.stdout.write('onData: ' + input + '\n');
Given how inputthen contains your data you'll need to use some method to extract the string of interest and then use parseInt. Perhaps a naive approach to your problem, assuming 1 integer per input:
鉴于如何input包含您的数据，您需要使用某种方法来提取感兴趣的字符串，然后使用parseInt. 假设每个 1 个整数，也许是解决问题的幼稚方法input：
var n = 0;
var m = 0;
var state = 0;
process.stdin.on('data', function (input) {
switch (state)
{
case 0:
// we're reading 'n'
n = parseInt(input.trim(), 10);
state++;
break;
default:
// we're reading 'm'
m = parseInt(input.trim(), 10);
if (state++ == n)
{
// we've read every 'm'
process.exit();
}
break;
}
});
I'm not a terribly large fan of this means of getting data to your NodeJS event loop, you should instead look to command line arguments, configuration/input files, or some other means.
我不太喜欢这种将数据传送到 NodeJS 事件循环的方法，您应该查看命令行参数、配置/输入文件或其他一些方法。
回答by Jorge Bucaran
回答by Jeremy J Starcher
This function will do what you asked for:
此功能将执行您的要求：
function readNums(s) {
// Split it up into numbers and spaces
var array = s.split(/(\d+)/);
// Keep just the numbers
array = array.filter(function(i) {return "" + +i == i});
// Convert back to a number
array = array.map(function(i) {return +i});
// How many elements should there have been?
var maxLen = array.shift();
if (array.length < maxLen) {
throw "Not enough enough numbers";
} else {
array.length = maxLen;
}
return array;
}
console.log(readNums("4 10 20 30 40 50 60 70"));
Result:
结果：
[10, 20, 30, 40]
