Reading multiple lines of data from a file
Question
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.
However I am only reading one line of code.
My Code - Opening File:
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
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:
0001:0002:0003:0021:CLS
Wanted output of data:
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. Any help will be much appreciated.
3 answers
solution1
1 ACCPTED 2014-12-05 10:16:46
You are overusing p_file for file to read as well as file to write.
if ((p_file = fopen(fileLocation, "w")) == NULL)
With this you are loosing pointer for file that you opened for reading. And as you close it in the else part fgets() thinks there are no more lines.
Use some other variable for file to write.
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.
solution2
1 2014-12-05 10:18:22
Your loop actually do the thing only one time
storedData.data = strtok(0, ":\\n");
so you just take the first line.
solution3
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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