Thread: More on pointers and strings

after alittle more time and errors i started working on more string and pointer functions, right now im confused.

Code:

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

int main() {
    char temp[20] = "tes_ting";  
    char temp2[20] = {'\0'};
    int Start = 2;    
    
    get_nextword(&temp, &temp2, '_', &Start, 8);
    
    printf("%s\n\n", temp2);
    
    return 0;
}

int get_nextword(char *src, char *dest, int sep, int *start, int max) {
    char *spot;
    
    if(max == '\0')
        max = strlen(src);
    
    copy(&src, &dest, &start, max);
    spot = strchr(dest, sep);
    dest[*spot] = '\0';
    
    return 0;
}

/* WORKING CODE...WORKING CODE...WORKING CODE...WORKING CODE...WORKING CODE...*/
int copy(char *src, char *dest, int *start, int end) {
    int x = 0;
    
    --*start;
    while(*start < end) {
        dest[x] = src[*start];
        
        ++*start;
        ++x;
    }
    
    return 0;
}

the get_nextword function is just supposed to take a string and return everything before the seperator(sep). the copy function does work so i dont get why this is crashing, its doesnt even give me any warnings (im stuck in DevC in Win XP). any ideas?

Your "WORKING CODE", does not appear to be working.

Try adding this to the function get_nextword(), in place of the call to copy():

printf("src | dest | start | max\n",src,dest,*start,max);
printf("%s | %s | %d | %d <--- before copy()\n",src,dest,*start,max);
copy(src, dest, &start, max);
printf("%s | %s | %d | %d <--- after copy()\n",src,dest,*start,max);
getchar();

See the results of what copy() does; I don't think it is what you planned. Could you please add some comments, so we can see what you are trying to do exactly?

In main() you have this:

>get_nextword(&temp, &temp2, '_', &Start, 8);

Here you want to pass the address of temp and temp2. Note that, because temp and temp2 are arrays, you should not put the & in front of the names. This:

get_nextword (temp,...

is the same as:

get_nextword (&temp[0],...

In both situations you pass the address of the first element of the array.

Also your call in get_nextword() to copy() should then be:

copy (src, dest, &start, max);

Avoid using constructions like this:

--*start;

They are legal C, but don't make code very readable. More readable would be:

(*start)--;

You don't need the variable max, just use strlen() always instead.

well, after checking my copy function I still say it works. ive done this a couple of times here before but its just supposed to take a inputted string and give what is inbetween start and end back.

get_nextword is like copy but instead of putting in a number/posistion you put in a char to stop it and max is just so you can end it quickly or if where the char is matters.

and with my pointer nightmare, why does this work? i thought a char was just a pointer to the first char, so the name is like -1 and the first char is 0. what am i missing here?

Code:

int main() {
    char temp[20] = "testing";  
    char temp2[20] = {'\0'};
    int spot = 2;
    
    copy(&temp, &temp2, &spot, 5);
    
    printf("%s", temp2);
    
    return 0;
}

if i have copy print all its args everything prints out fine except for dest. dest is just blank, but NULLed everything so that makes sense. and the code i just put up does print the right string with no errors/warnings.

thanks for the replies guys

any one?