C- Reading specific strings with quotes from a file - c

Question

I am trying to read strings from a file. File contains below text:
<1a>This is line 1<1a>
<2f>This is line 2<2f>
<3c>This is line 3<3c>
In my program I get this value 1a or 2f. Based on this, I need to extract that particular line like for 2f, I only need to read This is line 2 and save it in a buffer.
I have been able to read write using fopen fput but dont know how to read this.Can anyone please point me into some right direction which shows how to read this. Any demo code. Thanks.

Answer 1

This should do the trick:
#include <stdio.h>
#include <string.h>
int extract_line (char* line, char* buffer, char* ctag)
{
char line_buffer[255] = {0};
char* tagStart;
char* tagEnd;
if( strlen(line) < (sizeof(line_buffer)/sizeof(char)) )
{
strcpy(line_buffer,line);
}
else
{
printf("Line size is too big.\n");
return 1;
}
tagStart = strstr(line_buffer,ctag);
if(tagStart != NULL)
{
tagEnd = strstr(tagStart+1,ctag);
if(tagEnd != NULL && (tagEnd > (tagStart + strlen(ctag))))
{
*(tagEnd) = '\0';
strcpy(buffer, tagStart + strlen(ctag));
printf("%s\n",buffer);
}
else
{
printf("Could not find closing tag.\n");
return 1;
}
}
return 0;
}
int main ()
{
char buffer[255] = {0};
char line_buffer[255] = {0};
char tag[] = "<2a>";
char* cptr;
FILE* data;
data = fopen ("file.txt", "r");
if (data == NULL)
{
printf("\n Failed to open file!");
}
else {
while(( fgets( line_buffer, 255, data )) != NULL)
{
cptr = strstr(line_buffer,tag);
if(cptr == NULL)
{
continue;
}
if(!extract_line(line_buffer,buffer,tag))
{
//Do the rest of processing
puts(buffer);
strcpy(buffer,"");
}
}
fclose (data);
}
return 0;
}
Basicly, what you need to do is get the tag field and use it as a delimeter to exctract the token. Just get the line tag and then use it to exctract the data.

Answer 2

char* returnSpecificString(char* valueBetweenQuotes)
{
FILE* file= fopen("test.txt", "r"); // Open in reading only mode
char *line= malloc(sizeof(char[150]));
if (NULL == line) // Checks if enough memory
fprintf(stderr, "Not enough memory. \n");
else
{
while(fgets(line, sizeof(line), file)) //Iterate until end of file
{
if (strstr(line, valueBetweenQuotes) != NULL) // Meaning it's the line we want
return functionToExtractTextBetweenQuote();
}
}
return line;
}
As for the functionToExtractTextBetweenQuote() I advise you look functions like strtok() strchr()or sprintf() which will help you extract what you want from a string. I know this is unsufficiant but I ain't got the time to finish it now so I hope it will help you.