Search a string in a text file in C

Zykl0n-B · #1 (**permalink**) 04-16-2009

Hello,
I need help with a program i'm coding in C.

What my program has to do is to search a string in a text file, if it finds a match, print the string to stdout.

The file looks like:

000001 California
100000 Texas
011110 Ohio
010101 Washington

So, if the program finds a match, prints "100000 Texas" to stdout.

Could you help me?
Please excuse my poor english.

jim mcnamara · #2 (**permalink**) 04-16-2009

Code:

/* srch.c usage: srch filename "string to find"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv)
{
	FILE *fp=fopen(argv[1],"r");
	char tmp[256]={0x0};
	while(fp!=NULL && fget(tmp, sizeof(tmp), fp)!=NULL)
	{
		if (strstr(tmp, argv[2])
			printf("%s", tmp);
	}
	if(fp!=NULL) fclose(fp);
	return 0;
}

Zykl0n-B · #3 (**permalink**) 04-16-2009

Thank You!!!, Thanks man,... Thank you...

I corrected 'fgets' and 'if' functions...

Code:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main(int argc, char **argv)
{
        FILE *fp=fopen(argv[1],"r");
        char  tmp[256]={0x0};
        while(fp!=NULL && fgets(tmp, sizeof(tmp),fp)!=NULL)
        {
        if (strstr(tmp, argv[2]))
        printf("%s", tmp);
        }
        if(fp!=NULL) fclose(fp);
        return 0;
}

jim mcnamara · #4 (**permalink**) 04-17-2009

I failed typing - twice.

Zykl0n-B · #5 (**permalink**) 04-17-2009

I know

c0d1f1ed · #6 (**permalink**) 07-02-2009

Doesn't this fail when the search string crosses two 'tmp' block?

jim mcnamara · #7 (**permalink**) 07-02-2009

No the search is line-by-line, fgets gets one line at a time. tmp[256] can read in as many as 255 chars. No line in the example text is longer than 40. No issue.

As a general solution, use tmp[LINE_MAX] where LINE_MAX is defined in limits.h Most UNIX tools limit line size to whatever LINE_MAX is for your system.

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