重定向标准输入-C [英] Redirecting stdin - C

问题描述

因此，我打算通过执行以下命令来接受文本文件:

So I'm meant to accept a text file by doing the following command:

$ sort < list.txt 

我知道列表文本文件已输入到我的排序程序中，但是实际上我该如何使用程序中的信息?我怎么读?

I understand that the list text file is being inputted to my sort program, but how do I actually use the information inside my program? How do I read it?

我的代码:

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char** argv) {

    char c;   

    while (c != EOF){
        c = getchar();
        printf("%c ",c);
    }

   return (0);
}

示例:

$ ./sort.c < input.txt

./sort.c: line 3: $'\r': command not found

./sort.c: line 4: syntax error near unexpected token `('

'/sort.c: line 4: `int main(int argc, char** argv) {

推荐答案

当您在帖子中编写时，在命令行上使用"< "符号时，操作系统将读取文件并通过 stdin 将内容提供给您的程序.因此，您所需要做的就是阅读stdin.

When you use the '<' symbol on the command line as you have written in your post, the OS reads the file for you and gives the contents to your program via stdin. So, all you need to do is to read from stdin.

这是一个非常简单的代码段来演示-

Here is a very simple code snippet to demonstrate -

#include <stdio.h>

int main() {
    char line[256];
    FILE *fp = stdin;
    while(fgets(line, sizeof(line), fp) != NULL) {
        printf("%s", line);
    }
}

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