String length from the middle?

[mart_man00]

is it possible to figure out the string length to a certian part?

i mean if in a string you had testing, strlen would give back 7. Could i ask it the length to the first t? could i do it with memory address.

also i dont want to just add a '\0' to a string position, i want the strings to be unchanged at the end.

[Scarlet7]

This will find the number of chars to the word 'string' in Text, is this what you were looking for?

#include <stdio.h>
#include <string.h>
     
int main()
{
   char Text[] = "is it possible to figure out the string length to a certian part?";

   char *s1 = strstr(Text, "string");
   int len =  s1-Text;
   printf("Length to 'string' = %d\n", len);
   return 0;
}

[ronin]

will this work for you?

#include <stdio.h>

int main()
{
  char str[] = "where is this >!< located?";
  int length, i;
 	
  length = 0;
  for(i=0; str[i] != '\0'; i++)
 {
    if(str[i] == '!')
       { length++; break; }
 	  
   length++;
 }
 	
 printf("%s\n", str);
 	
 for(i=0; i < length-1; i++)
   putchar(' ');
    
 putchar('^');
    
 printf("\n%c found at position %d",
           str[length-1], length);
 	  
 return 0;
}

[mart_man00]

i want output back like that, but it seems like its cheating. what if "string" is in a string more than once?

i mean i have something like this

char text[] = "is it possible to figure out the string length to a certian part?";
char *spot = text;
++*spot;

searching for a strings seems like its a long and slower way of doing it. but your way is a good fake.

[Scarlet7]

I'm still not 100% sure what you are looking for? What is the cryteria for finding the position in the text. There's not a quick way of searching thought strings in C. Here are a few more examples.

#include <stdio.h>
#include <string.h>
int main()
{
   char text[] = "is it possible to figure out the string length to a    certian part?";
   char *spot = text;

   while(*spot && *spot != 'f')
		++spot;
   printf("Count to 'f' = %d\n", spot-text);

   spot = text;
   char* find = "figure";
   while(*spot && strncmp(spot, find, strlen(find)))
		++spot;
   printf("Count to 'figure' = %d\n", spot-text);
   printf("The rest of the text = %s\n", spot);
   printf("strlen from 'figure' = %d\n", strlen(spot));
   return 0;
}

[mart_man00]

all i want it to beable to do is use a memory address like a '\0' with out changing the strings

i tried subtracting addresses but i got a error(i did this on my windows laptop, my linux desktop fan died and it over heats to quick).

[Scarlet7]

You've still lost me? The '\0' in a string indicates the end of the string. You say you want to use it? if need to know
the address of '\0' its:

char string[] = "a string"
char *address = string + strlen(string);

If yo'ure trying to use memory address = '\0' = 0 then that will crash the program.
Post some code.

[mart_man00]

!@#$%^&*

char temp[] = "this is a string, just a string";
char *spot = temp;
*spot += 3;


now, if i call strlen(temp) i get 31. strlen goes threw the string until it finds a \0. while its doing this it increments a var to return.

the probelm with that is it will only stop when it fines a \0. i would like to calculate length of temp to a memory address not a \0.

i dont want to use spot as a string and call strstr and find the start of it (but, that would work), that seems like more over head thats not really needed.

i tried subtracting addresses

int strlento(char *start, char *end) {
return (&end - &start);
}

but i get a crash.

any one get the idea?

[Scarlet7]

The problem is that you're using the address of pointers to calculate, which is a pointer to a pointer. Remove the & as 'end' and 'start' are already pointers.

int strlento(char *start, char *end) { 
return (end - start);
}

> i would like to calculate length of temp to a memory address not a \0.

I don't know understand what you mean?

[mart_man00]

with out the &s i get NULL returned.

> i would like to calculate length of temp to a memory address not a \0.

I don't know understand what you mean?

!@#$%^&*

NOW WITH STRLEN IT GIVES BACK THE LENGTH OF THE STRING BY LOOKING FOR A \0 AND COUTING HOW MANY TIMES IT DIDNT HIT IT. I WOULD LIKE IT TO STOP AT A CERTIAN MEMORY ADRRESS, NOT JUST \0. SO I WANT TO MAKE A ADDRESS LIKE \0 BUT NOT \0.

sorry, but this is driving me nuts. this function probally has the simplest thing wrong and i still cant see it

[Scarlet7]

Any closer?

#include <stdio.h>
#include <string.h>

// count to address or '\0' which ever comes first
int my_strlen(char *text, char *PleaseStopCountingAtThisAddress)
{
	char *start = text;
	while(*text && text != PleaseStopCountingAtThisAddress)
		text++;
	return text-start;
}
int main()
{
   char text[] = "is it possible to figure out the string length to a certian part?";

   char *PleaseStopCountingAtThisAddress = &text[25]; // 'o'	in out
   int len = my_strlen(text, PleaseStopCountingAtThisAddress);

   printf("len = %d  char at PleaseStopCountingAtThisAddress = %c\n", len, *PleaseStopCountingAtThisAddress);

//OR

   len = PleaseStopCountingAtThisAddress-text;
   printf("len = %d\n", len) ;
}

If not post your code

[Hammer]

Are you after strcspn() ?

#include <stdio.h>
#include <string.h>

int my_strlen(const char *s, char c)
{
  int len = 0;
  while (*s && *s != c) {len++; s++;}
  return len;
}

int main(void)
{
  char s1[] = "This is a ! test";
  puts (s1);
  printf ("length to ! is %d\n", my_strlen(s1, '!'));
  printf ("length to ! using strcspn() is %d\n", strcspn(s1, "!"));
  return(0);
}

/*
This is a ! test
length to ! is 10
length to ! using strcspn() is 10
*/

[mart_man00]

no, thats looking for a character. i know the memory address. i get errors when i subtract the address.

i know some one can do this.

[quzah]

int lengthto( const char * s, int tofirst )
{
    char * ptr = strchr( s, tofirst );
    if( ptr )
        return ptr-s;
    return -1;
}

How hard is that?

[edit]

int fromtolength( const char *s, int start, int tonext )
{
    char *ptr = strchr( s+start, tofirst );
    if( ptr )
        return ptr-(start+s);
    return -1;
}

There. There's another version.
[/edit]
Quzah.

[mart_man00]

char * ptr = strchr ( s, tofirst );

why are you using strchr to SEARCH!!!. if it so dam easy why cant some on do it with out searching. how many times have i said that already. i dont mine if other people cant do it(we already know i cant), how many ..........ing times does it need to be said!!! DONT USE A SEARCH!!!!IT WILL JUST GIVE ME THE FIRST OCCURANCE AND IT MAYBE THE SECOND OR THIRD OR WHATEVER-TH!!!! USE ADDRESS AND IF POSSIBLE TELL ME WHY MY ATTEMPT TO SUBTRACT MEMORY ADDRESS FAILED!!!!

ive been looking at this for way to long...........................................