C read conf file

Question

Hello i have a problem when i try to read conf file (line by line)

this is my code :

bool EndWith(const char* haystack, const char* needle)
{
    bool rv = 0;
    if (haystack && needle)
    {
        size_t needle_size = strlen(needle);
        const char* act = haystack;
        while (NULL != (act = strstr(act, needle)))
        {
            if (*(act + needle_size) == '\0')
            {
                rv = 1;
                break;
            }
            act += needle_size;
        }
    }

    return rv;
}
    FILE *file2 = fopen ("config.conf", "r");
    const size_t line_size = 300;
    char* line = malloc(line_size);
    while (fgets(line, line_size, file2) != NULL)  {
        puts(line);

        if(EndWith(line, "toto")) {
            puts("yes");
        }
    }

and my conf file :

vm.user_reserve_kbytes = 131072 toto
vm.vfs_cache_pressure = 100 toto
vm.zone_reclaim_mode = 0 toto

My code return 2 "Yes" but if my conf file, if i add a line feed in first line i read my 3 lines and my code return 3 "Yes" Why ?

i want to return 3 "Yes" without need to add a line feed in line0 of my conf file

bug retrurn :

vm.user_reserve_kbytes = 131072 toto

yes
vm.vfs_cache_pressure = 100 toto

yes
vm.zone_reclaim_mode = 0 toto

correct return (with add a line feed)

yes
vm.user_reserve_kbytes = 131072 toto

yes
vm.vfs_cache_pressure = 100 toto

yes
vm.zone_reclaim_mode = 0 toto

i tested solution Filip Kočica (thanks for your help) but i have same problem :

the code:

bool EndWith(const char* haystack, const char* needle)
{
    if (haystack == NULL || needle == NULL)
    {
        return false;
    }
    const char* p;
    if ((p = strstr(haystack, needle)) != NULL)
    {
        if (!strcmp(p, haystack + strlen(haystack) - strlen(needle)))
        {
            return true;
        }
    }
    else
    {
        return false;
    }
    return false;
}



int main(int argc, char **argv)
{
        FILE *file2 = fopen ("config.conf", "r");
        const size_t line_size = 300;
        char* line = malloc(line_size);
        while (fgets(line, line_size, file2) != NULL)  {
            puts(line);

            if (EndWith(line, "za"))
            {
                puts("it does.");
            }

        }



        return 0;
}

my file config.conf :

vm.user_reserve_kbytes = 131072 za
vm.vfs_cache_pressure = 1001 za
vm.zone_reclaim_mode = 01 za

Does your file finishing by an `\n` ? (Without, the last line is not finishing by `\n` and so will no print `yes`) — NatNgs, Aug 08 '17 at 12:27
i edit my message, it's not "space line" but "a line feed", sorry — user7454761, Aug 08 '17 at 12:28
It appears that the last line of your file doesn't have a linefeed at the end. — Bob Jarvis - Слава Україні, Aug 08 '17 at 12:28
when calling `fopen()`, always check (!=NULL) the returned value to assure the operation was successful. — user3629249, Aug 09 '17 at 03:16
when calling `malloc()`, always check (!=NULL) the returned value to assure the operation was successful. — user3629249, Aug 09 '17 at 03:16
this statement: `if (!strcmp(p, haystack + strlen(haystack) - strlen(needle)))` will probably fail on every line that ends with '\n' — user3629249, Aug 09 '17 at 03:21

kocica · Accepted Answer · 2017-08-08T14:53:47.237

1

1]

It return's 2 becouse last row doesn't end with new line character \n.

Everytime you call getline it gives you one line from file (If there is another line). There is no need for checking if this line really end's with NL character. Just count how many times getline didn't return EOF.

Get puts out of condition

while (fgets(line, line_size, file2) != NULL)
{
    puts(line);
    puts("yes");

    if(EndWith(line, /*special strings*/ ))
    {

    }
}

2]

bool EndWith(const char* haystack, const char* needle)
{
    if (haystack == NULL || needle == NULL)
    {
        return false;
    }
    const char* p;
    if ((p = strstr(haystack, needle)) != NULL)
    {
        if (!strcmp(p, haystack + strlen(haystack) - strlen(needle) - 1))
        {
            return true;
        }
    }
    else
    {
        return false;
    }
    return false;
}



int main(int argc, char **argv)
{
        FILE *file2 = fopen ("config.conf", "r");
        const size_t line_size = 300;
        char* line = malloc(line_size);
        while (fgets(line, line_size, file2) != NULL)  {
            if (EndWith(line, "za"))
            {
                puts("it does.");
            }

            puts(line);
        }



        return 0;
}

config file:

vm.user_reserve_kbytes = 131072 za
vm.vfs_cache_pressure = 1001 za
vm.zone_reclaim_mode = 01 za

OUTPUT:

it does.
vm.user_reserve_kbytes = 131072 za

it does.
vm.vfs_cache_pressure = 1001 za

it does.
vm.zone_reclaim_mode = 01 za

edited Aug 08 '17 at 14:53

answered Aug 08 '17 at 12:27

kocica

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i want to check if my line end with special strings, i inspired by this link : https://stackoverflow.com/questions/874134/find-if-string-ends-with-another-string-in-c but yes i think i have problem with \n and eof – user7454761 Aug 08 '17 at 12:39
Ok so check for _special strings_, but not for `\n` :-) – kocica Aug 08 '17 at 12:43
Yes, i edit my message, i want to check if my line end with "toto" – user7454761 Aug 08 '17 at 12:49
I've did it for you, it should work. Just replace function `EndWith`. – kocica Aug 08 '17 at 13:03
thanks for your help, but i have same problem, i add your code in new message – user7454761 Aug 08 '17 at 13:59
Np, glad it helped. But code i posted work's so you should mark it as answered :-) – kocica Aug 08 '17 at 14:12
@user7454761 NOW it finally work's as you want (updated answer), i didnt notice what you exactly want to do. :-) – kocica Aug 08 '17 at 14:54

C read conf file

1 Answers1