[英]Reading a text file and ignoring commented lines in C
I'm currently working on making a tiny computer in C for a programming assignment and I'm stuck on one part. 我目前正在用C语言制作一台微型计算机以进行编程任务,但我只停留在一部分上。
I'm stuck on how to correctly ignore comments in a text file that I'm reading in. (Example of file input below). 我一直在研究如何正确忽略正在阅读的文本文件中的注释。(下面的文件输入示例)。
Input File
5 5 //IN 5
6 7 //OUT 7
3 0 //STORE 0
5 5 //IN 5
6 7 //OUT 7
3 1 //STORE 1
1 0 //LOAD 0
4 1 //SUB 1
3 0 //STORE 0
6 7 //OUT 7
1 1 //LOAD 1
6 7 //OUT 7
7 0 //END
The first input on each new line is an operation, the 2nd input being an address. 每条新行的第一个输入是一个操作,第二个输入是一个地址。 I am planning to have a switch statement for each op and then calling the appropriate function. 我计划为每个操作准备一个switch语句,然后调用适当的函数。 This is my current layout for reading in the file: 这是我当前读取文件的布局:
//file handling
int c;
FILE * file;
file = fopen(name, "r");
if (file){
printf("Run.\n");
while ((c = getc(file)) != EOF){
op = c;
switch (op){
case 5:
print("Inside case 5\n");
}
}
fclose(file);
}
How can I ignore the // on each line and skip to the next line in the file? 如何忽略每行// //并跳至文件的下一行?
Call fgets to get a full line: 致电fgets以获取完整行:
fgets(buffer, 100, file);
and then extract the two numbers from the line: 然后从该行中提取两个数字:
sscanf(buffer, "%d%d", &instruction, &address);
how to correctly ignore comments in a text file that I'm reading in 如何正确忽略正在阅读的文本文件中的注释
How can I ignore the // on each line and skip to the next line in the file? 如何忽略每行// //并跳至文件的下一行?
Read the line using fgets()
使用fgets()
阅读该行
char buf[80];
if (fgets(buf, sizeof buf, file)) {
Look for the //
with strstr()
@Steve Summit and lop off the string at that point. 使用strstr()
@Steve Summit查找//
,然后在该位置断开字符串。
char *slash_slash = strstr(buf, "//");
if (slash_slash) {
*slash_slash = '\0';
}
Continue processing the line as desired. 根据需要继续处理生产线。
...
}
By using fgets
and strtok
you can read line by line and split the string acording to the //
delimiter. 通过使用fgets
和strtok
您可以逐行阅读并根据//
分隔符分割字符串。 Here's an example (it is not fully checked, but it's the main idea): 这是一个示例(尚未完全检查,但这是主要思想):
FILE *f = fopen("file.txt", "r");
if (f== NULL)
{
printf("opening file failed\n");
return 1;
}
char buf[256] = { 0 };
while (fgets(buf, 256, f))
{
char *s = strtok(buf, "//");
if (s == NULL)
{
printf("s == NULL\n");
}
else
{
printf("%s\n", s);
}
memset(buf, 0, 256);
}
fclose(f);
EDIT: I just realized that this is not exactly what you were looking for. 编辑:我只是意识到这不是您想要的。 However, you can still use it in order to first ignore the comment, and then break the given string into operation and address, or whatever that is... 但是,您仍然可以使用它来首先忽略注释,然后将给定的字符串分成操作和地址,或其他任何东西。
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