Searching Strings

**kinghajj** · 05-11-2004

is there a function that searches a string until another string is found in it, and then returns the position of that?

Example:

Code:

...
char string1[] "Hello, how are you?";
char string2[] "are";
int i = search(string1, string2);
..

If not, then has anybody written a function like that that I can use?

**kinghajj** · 05-11-2004

Nevermind, I think I've found the correct function: strcspn.
Sorry for posting before searching again

**chrismiceli** · 05-11-2004

look into
strstr()
and
strchr()
strstr() - http://www.rt.com/man/strstr.3.html
strchr() - http://www.rt.com/man/strchr.3.html

**kinghajj** · 05-11-2004

Thx. (strchr looks usefull, too).

If anyone's wondering, I'm trying to make a virtual machine, and need this function to locate parts of the virtual hard drive file (to locate virtual files in that file).

**quzah** · 05-11-2004

As a quick hack, why not create an index file then? Whenever a file is written, store its offsets (start, and end), file name, etc, in a file. Then just sort that or have it in memory, or what not. fseek to the areay, read the block(s) of the file...

Quzah.

**kinghajj** · 05-11-2004

Nah: I've already written a function that works fine with what I want to do. But, that's a good idea.

My only problem now (which I'm asking help for elsewhere) is the bytecode (but, as I said, I'm getting help with that elsewhere). Hopefully, it won't be that hard.

**kinghajj** · 05-11-2004

Actually, I have another question:

is there a file-writing function that overwrites the data, and leaves the other alone (if the user edit's a file, I'll just want to fseek() to the file, and start editing there, without having to re-write the rest afterwards)

**Kip Neuhart** · 05-12-2004

Originally Posted by kinghajj

Actually, I have another question:

is there a file-writing function that overwrites the data, and leaves the other alone (if the user edit's a file, I'll just want to fseek() to the file, and start editing there, without having to re-write the rest afterwards)

All file I/O will overwrite the current data. What you have to worry about is the relative length of the new data compared to the old data. Files will typically not shrink and expand when you try to update them. The usual solution to this problem is to rewrite the entire file.

**kinghajj** · 05-12-2004

Strcspn doens't work: it doesn't look for what I'm looking for as a whole, but rather looks for the first occurance of any of the characters I give

I need a function that finds it as it appears as a whole, not individual characters! I've look, but can't find one

**quzah** · 05-12-2004

Originally Posted by kinghajj

Strcspn doens't work: it doesn't look for what I'm looking for as a whole, but rather looks for the first occurance of any of the characters I give

I need a function that finds it as it appears as a whole, not individual characters! I've look, but can't find one

Asked, and answered:

Originally Posted by chrismiceli

strstr() - http://www.rt.com/man/strstr.3.html

Quzah.

**kinghajj** · 05-12-2004

I got it to work... thx for all your help...

now... on to the bytecode!!! (I'll probably be back here soon, lol

)

**sand_man** · 05-13-2004

char *strchr(const char *s, int c);

char *strrchr(const char *s, int c);

DESCRIPTION
The strchr() function returns a pointer to the first
occurrence of the character c in the string s.

The strrchr() function returns a pointer to the last
occurrence of the character c in the string s.

Can i ask why does it say "returns a pointer to the last
occurrence of the character c" when in the example "c" is an integer?

**quzah** · 05-13-2004

Code:

#include <stdio.h>
int main( void )
{
    int x;
    char y = 'a';

    x = y;
    printf("y has the character value of %c, and has the decimal value of %d.\n", y, y );
    printf("x has the character value of %c, and has the decimal value of %d.\n", x, x );

    return 0;
}

char is an integeral data type. That is to say, it can be represented as an integer.

Quzah.

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