从文件中读取多行数据
[英]Reading multiple lines of data from a file
问题描述
I am reading data from a pre-read file and storing it in a buffer in which I have ran through a struct to organise the data to then re-save it in another file. 
我正在从预读的文件中读取数据，并将其存储在缓冲区中，在该缓冲区中，我遍历了一个结构以组织数据，然后将其重新保存在另一个文件中。
However I am only reading one line of code. 但是我只读一行代码。
My Code - Opening File: 我的代码-打开文件：
File *p_file
char fileLocation[40];
char buff[1000];
printf("\nEnter file name: \n");
scanf("%s, fileLocation);
p_file = fopen(fileLocation, "r");
if(!p_file)
{
printf("\nError!\n");
}
Loop to read data and save file 循环读取数据并保存文件
while(fgets(buff, 1000, p_file)!=NULL
{
printf("%s", buff);
storedData.source = atoi(strtok(buff, ":");
storedData.destination = atoi(strtok(0, ":");
storedData.type = atoi(strtok(0, ":");
storedData.port = atoi(strtok(0, ":");
storedData.data = strtok(0, ":\n");
printf("\nEnter a File Name to save:");
scanf("%s", fileLocation);
if ((p_file = fopen(fileLocation, "w")) == NULL
{
puts("\n Could not point to the file.");
}else{
printf("\nSaving");
fprintf(p_file, "%04d:%04d:%04d:%04:%s \n",
storedData.source,
storedData.destination,
storedData.type,
storedData.port,
storedData.data );
fclose(p_file);
}
fclose(p_file);
Current output of data: 当前数据输出：
0001:0002:0003:0021:CLS
Wanted output of data: 想要的数据输出：
0001:0002:0003:0021:CLS
0001:0010:0003:0021:CLS
0001:0002:0002:0080:<HTML>
I believe I must declare an integer value to use to loop through the file contents as well as use malloc to get the size of the struct but I do not know how I would go about doing this. 我相信我必须声明一个整数值以用于遍历文件内容以及使用malloc来获取结构的大小，但是我不知道该怎么做。 Any help will be much appreciated. 任何帮助都感激不尽。
3 个解决方案
解决方案1
1 已采纳 2014-12-05 10:16:46
You are overusing p_file for file to read as well as file to write. 您正在过度使用p_file来读取文件和写入文件。
if ((p_file = fopen(fileLocation, "w")) == NULL)
With this you are loosing pointer for file that you opened for reading. 这样，您就失去了打开阅读文件的指针。 And as you close it in the else part fgets() thinks there are no more lines. 当您在else部分中关闭它时， fgets()认为不再有任何行。
Use some other variable for file to write. 使用其他一些变量来写入文件。
If you want to work on buffered data then change your while(fgets()... to read all lines and then work on each line. fgets() will not read multiple lines. 如果要处理缓冲的数据，请更改while(fgets()...以读取所有行，然后在每一行上工作fgets()不会读取多行。
解决方案2
1 2014-12-05 10:18:22
Your loop actually do the thing only one time 你的循环实际上只做一次
storedData.data = strtok(0, ":\\n");
so you just take the first line. 所以你只要走第一行。
解决方案3
0 2014-12-05 11:19:46
FILE *in_file;
FILE *out_file;
char fileLocation[40];
char buff[1000];
printf("\nEnter file name: \n");
if( 1 != scanf(" %s, fileLocation) )
{
perror( " scanf failed for input file: );
exit( EXIT_FAILURE );
}
if( NULL == (in_file = fopen(fileLocation, "r") )
{
perror( "fopen failed for input file" );
exit( EXIT_FAILURE );
}
printf("\nEnter a File Name to save:");
if( 1 != scanf(" %s", fileLocation) )
{
perror( "scanf failed for outut file name" );
fclose( in_file ); // cleanup
exit( EXIT_FAILURE );
}
if ( NULL == (out_file = fopen(fileLocation, "w")) )
{
perror( " fopen failed for output file" );
fclose( in_file ); // cleanup
exit( EXIT_FAILURE )l
}
while(fgets(buff, 1000, p_file)!=NULL) )
{
printf("%s", buff);
storedData.source = atoi(strtok(buff, ":");
storedData.destination = atoi(strtok(0, ":");
storedData.type = atoi(strtok(0, ":");
storedData.port = atoi(strtok(0, ":");
storedData.data = strtok(0, ":\n");
printf("\nSaving");
fprintf(p_file, "%04d:%04d:%04d:%04:%s \n",
storedData.source,
storedData.destination,
storedData.type,
storedData.port,
storedData.data );
} // end while
fclose( in_file ); // cleanup
fclose( out_file ); // cleanup
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