Thread: Flip words in a char array.

Code:

char *y=calloc(1,strlen(s)+1);
char *p=s+strlen(s);

You dint check the return value of calloc and dont really see the point of this

Code:

if( !strchr(delims,*s) )
    strcat(y,s);

ssharish

Originally Posted by mherald81

What's the difference between calloc and malloc?

calloc - allocated the memory and initialises the allocated memory to 0
malloc - allocated memory but dosn't initialise the allocated memory

ssharish

Originally Posted by mherald81

It's mainly the strcat line that I'm lost on because all of that is on one line with a comma separating them.

That is just a (misguided) attempt to make the code more concise. It could have been written as:

Code:

char *wordrev(char *s, const char *delims)
{
    char *y = calloc(1, strlen(s) + 1);
    char *p = s + strlen(s);
    while (p != s)
    {
        if (strchr(delims, *--p))
        {
            strcat(y, p + 1);
            strncat(y, p, 1);
            *p = 0;
        }
    }
    if (!strchr(delims, *s))
    {
        strcat(y, s);
    }
    strcpy(s, y);
    free(y);
    return s;
}

Originally Posted by laserlight

That is just a (misguided) attempt to make the code more concise. It could have been written as:

Code:

char *wordrev(char *s, const char *delims)
{
    char *y = calloc(1, strlen(s) + 1);
    char *p = s + strlen(s);
    while (p != s)
    {
        if (strchr(delims, *--p))
        {
            strcat(y, p + 1);
            strncat(y, p, 1);
            *p = 0;
        }
    }
    if (!strchr(delims, *s))
    {
        strcat(y, s);
    }
    strcpy(s, y);
    free(y);
    return s;
}

So strcat(y, p+1) concatenates without the space at the beginning of p and strncat(y,p,1) concatenates the space at the end. And *p=0 sets where p is pointing to in memory to 0? And the loop will continue until p and s are pointing at the same address in memory?