调试 read() 系统调用 - 在按下 CTRL-C 之前不会继续执行
您好，我需要使用系统调用 read() 来读取 I/O。我有以下代码，
//Reading in the commands
for(;;) {
n = read( fd, buf, 128 );
fflush(stdin);
printf("---\n");
}
它不会打印“---”字符串，直到我终止程序，然后它会立即打印所有内容。我也尝试过刷新输入流，但没有成功。我对 read() 不太熟悉，所以我不太清楚它是如何工作的。我需要使用 read() 的原因是因为我需要让 CTRL-D 终止程序。有人愿意告诉我为什么会发生这种情况以及如何继续吗？提前致谢。
PS：我做了一些更多的测试，得到了一个有趣的结果：
for(i;i<3;i++) {
if( read( fd, buf, 128 ) < 0) {
printf("Read returned less than 0");
} else {
printf("Read is working\n");
}
}
删除“\n”字符使其在读取第三个输入后打印“Read isworking”3次。那里有字符将使其在读取每个输入后打印。
Hi I need to use the system call read() to read from I/O. I have the following code
//Reading in the commands
for(;;) {
n = read( fd, buf, 128 );
fflush(stdin);
printf("---\n");
}
It will not print the "---" string until I I terminate the program, then it'll print all at once. I've tried flushing the input stream as well with no luck. I'm not very familiar with read() so I don't exactly know how it works. The reason I need to use read() is because I need to make CTRL-D terminate the program. Would anyone mind enlighten me as to why is this happening and how to proceed? Thanks in advance.
PS: I did some more testing an got an interesting result:
for(i;i<3;i++) {
if( read( fd, buf, 128 ) < 0) {
printf("Read returned less than 0");
} else {
printf("Read is working\n");
}
}
removing the "\n" character makes it print "Read is working" 3 times after the third input is read. having the character in there will make it print after each input is read.
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您需要检查“read”的返回值以检测 STDIN 上的 EOF（即按 Ctrl-D）。您发布的代码是无限循环。
You need to check the return value of ‘read‘ to detect EOF on STDIN (i.e. pressing Ctrl-D). The code you posted is an infinite loop.
我仍然不知道为什么要这样做，但是在再次循环之前 fflush(stdout) 解决了问题。
对于我的原始代码：
解决了问题。仍然想知道为什么需要这样做。
I still don't know why it was doing that but
fflush(stdout)before it loops again solves the problem.for my orginal code:
solved the problem. Still wondering why this needs to be done.