Eclipse CDT火星：来自文件的输入 [英] Eclipse CDT Mars: Input from a file
问题描述
我最近安装了用于运行C程序的Eclipse CDT Mars版本。我从文件中获取输入时遇到问题。所以，我有一个看起来像这样的程序：
I have recently installed Eclipse CDT Mars release for running C Programs. I am facing problems with taking input from a file. So, I have a program that looks like this:
int main(void) {
//Declarations
int number_of_segments;
int k_constraint;
segment_node *ptr_to_segment_array, *ptr_to_segment_sorted_array;
int no_of_coordinates;
int *ptr_to_solution_array;
int *ptr_to_list_of_segment_identifiers_currently;
int no_of_identifiers_currently=1;
int i,j=1,k=0, l=0;
//setvbuf(stdout, NULL, _IOLBF, 0);
//Input
printf("Enter the number of segments\n");
scanf("%d", &number_of_segments);
printf("Enter the k constraint \n");
scanf("%d", &k_constraint);
no_of_coordinates = number_of_segments*2;
//Dynamically allocate memory to the Array
ptr_to_segment_array = (segment_node*)malloc(sizeof(segment_node)*no_of_coordinates);
ptr_to_segment_sorted_array = (segment_node*)malloc(sizeof(segment_node)*no_of_coordinates);
ptr_to_solution_array = (int*)malloc(sizeof(int)*no_of_coordinates);
ptr_to_list_of_segment_identifiers_currently = (int*)malloc(sizeof(int)*number_of_segments);
/*Now, input the individual segments's coordinates from left to right
** while also assigning the unique numbers to an individual segments' coordinates*/
printf("Enter the coordinates of segments from left to right \n");
for(i=0; i<no_of_coordinates; i++,j++){
scanf(" %d", &(ptr_to_segment_array[i].coordinate));
if(j==1){
ptr_to_segment_array[i].position = 'l';
ptr_to_segment_array[i].identifier = i+1;
}
else if(j==2){
ptr_to_segment_array[i].position = 'r';
ptr_to_segment_array[i].identifier = i+1;
}
if(j==2){
//Reset
j=1;
}
}
return 0;
}
当然，不是整个程序。这就是它的一瞥。问题是scanf语句应该接受输入，而我希望输入来自文件。因此，我执行了以下操作：
Well, of course its not the whole program. This is the glimpse of it. The problem is the scanf statements are supposed to take input and I want the input to be taken from a file. So, I did the following:
- 首先，我在工作区目录中创建了一个包含以下内容（输入）的文本文件
3
2
-3
2
0
5
3
8
- 然后，我将Eclipse配置为从控制台获取输入。
请注意，编码已设置为MS932（默认）
Notice that the Encoding has been set to MS932(default)
现在，我构建它并对其进行调试。我进入输入步骤。然后，我等了几分钟，什么也没有。而已。该程序似乎需要很长时间，但控制权不会移至下一行。
Now, I build it and debug it. I step up to the Input step. Then, I wait for like minutes and nothing. That's it. The program seems to be taking long time but control doesn't move to the next line.
现在，您可能会认为程序中存在一些错误本身，是的，但是我也使用自定义输入在Ideone.com上运行了该程序，它确实接受了输入。另外，我用Console的输入运行了该程序，它确实一步一步正确地接受了输入。
Now, you may think that there is some fault in the program itself and yeah it may be but I also ran this program on Ideone.com with custom inputs and it does take the inputs. Also, I ran this program with input from Console and it did take the inputs properly step by step.
所以，为什么它不接收来自控制台的输入呢？这样直接归档吗？是Notepad / Eclipse或其他问题的编码问题吗？
So, why it wouldn't take inputs from a file directly this way? Is it an encoding issue with Notepad/Eclipse or something else?
我们将提供任何帮助。
顺便说一句，如果有人想要完整的程序，我很乐意提供。它不是一些专有内容。我纯粹是出于教育目的而写的，目的是解决某些问题。
Any help is appreciated.
Btw, if anyone wants the complete program, I am happy to provide it. Its not some proprietary content. I wrote purely for educational purpose as solution to some problem.
推荐答案
我还没有看到您告诉过您程序从文件中读取。因此，它只是等待您的输入。
您应该在开头添加它：
I haven't seen that you tell your program to read from file. So it just waits your input.
You should add this at the beginning:
freopen("input.txt", "r", stdin);
功能：它重新打开 s stdin 文件描述符，并将 input.txt 附加到文件描述符。它附有用于读取的内容-第二个参数是 r
What it does: it reopens stdin file descriptor and attaches input.txt to it. It attaches it for reading - second argument is "r"
但是如果您希望能够读取控制台和文件，您需要再添加一个：
But if you want to be able to read from console AND files, you need to add one more:
FILE *in;
in = fopen("input.txt", "r");
您应该替换 scanf（...）与 fscanf（in，...）
fscanf(in, "%d", number);
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