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Old 06-11-2003, 02:33 PM   #1
Linh
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Registered: Apr 2003
Posts: 178

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strcmp function does not seemed to work


strcmp function does seemed to work
result = strcmp (word, "FIREWALLGROUP=0"); this should be 0
but it is a 1. Nowhere in the code did I add a null (\0) character to
the array word.

word should be equal to FIREWALLGROUP=0

===============================
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

int main()

{

FILE *file_pointer;
int i = 0;
char single_char;
char word[15];
int result = 99;

/*The statement below should yield FIREWALLGROUP=0 */
file_pointer = popen("cat /etc/yellowbox/network-config|grep FIREWALLGROUP | awk '{print $1}'", "r");

while(!feof(file_pointer))
{
single_char = getc(file_pointer);
word[i] = single_char;
printf("i = %d %c\n", i, word[i]);
i++;
}

printf("word = %s", word);
result = strcmp (word, "FIREWALLGROUP=0");
printf("result = %d\n", result);
====================================
The output result is shown below

root:~# ./test1
i = 0 F
i = 1 I
i = 2 R
i = 3 E
i = 4 W
i = 5 A
i = 6 L
i = 7 L
i = 8 G
i = 9 R
i = 10 O
i = 11 U
i = 12 P
i = 13 =
i = 14 0
i = 15

i = 16 ˇ
word = FIREWALLGROUP=0
ˇ•ˇresult = 1
 
Old 06-11-2003, 04:24 PM   #2
dorian33
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Registered: Jan 2003
Location: Poland, Warsaw
Distribution: LFS, Gentoo
Posts: 587

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try:
char word[16];

string "FIREWALLGROUP=0" is 15 chars + null byte
-----
loop:

while(!feof(file_pointer)) {... }

ends with i=16; index is out of range! (max is 14)
you need to control 'i' value inside the loop:
if(i++ >sizeof(word)) break;
 
Old 06-12-2003, 01:10 AM   #3
yrraja
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Registered: Sep 2002
Distribution: RH, FC, Ubuntu, Solaris, AIX
Posts: 114

Rep: Reputation: 15
All the string related functions like strcmp expect null terminated strings as parameters. The string that you were reading with 'file_pointer ' did not have a null character after '=0', therefore for strcmp function there was more data after '=0' too. In this scenario strcmp will read all the data from the start of the array 'word' until a null character is detected.

For your case you can also use 'strncmp()' function like this:

result = strncmp (word, "FIREWALLGROUP=0", 15);

Yaser
 
Old 06-12-2003, 05:48 AM   #4
Linh
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Registered: Apr 2003
Posts: 178

Original Poster
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rate

Hi. I clicked on the button Affero. A new page comes up.
I rate the service on step 1
I enter the Affero Username: linh
Affero Password: my password

INVALID (Please note: Username and Password fields are case sensitive)

I cannot rate you or donate to the site.
How do I donate to this site ?
I like the service.
 
Old 06-12-2003, 06:09 AM   #5
yrraja
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Posts: 114

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To rate/donate you have to be the member of afferno. Your have to register there first and after that u can rate someone. This username/password is saperate from the one you have at linuxquestions.org

Yaser
 
  


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