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Is there a function for string rotate ?

"This is a string. "

Rotate to :
"his is a string. T"

Rotate to :
"is is a string. Th"

....

I use it for LCD Display for Scroll.

Parents

0 Drew Davis over 21 years ago in reply to erik malund

Off the top of my head:

char* strrol (char* src)
    {
    char* d = src;
    char* s = d + 1;
    char c = *d;

    while (*s++)
        {
        *d++ = *s;
        }

    *d++ = c;
    *d = 0;
    } // strrol

That will cost you a lot of time, though, copying the string over and over. You could simply have back-to-back copies of the string. Or, change your transmit routine to use a modular offset and send the string in two pieces:

void send (char* s, int offset)
    {
    int l = strlen(s);
    int i;

    for (i = offset; i < l; ++i)
        {
        OutputToLcd (s[i]);
        }
    for (i = 0; i < offset; ++i)
        {
        OutputToLcd (s[i]);
        }

    }

Lots of ways to get this result, with different speed/space tradeoffs.

Reply

0 Drew Davis over 21 years ago in reply to erik malund

Off the top of my head:

char* strrol (char* src)
    {
    char* d = src;
    char* s = d + 1;
    char c = *d;

    while (*s++)
        {
        *d++ = *s;
        }

    *d++ = c;
    *d = 0;
    } // strrol

void send (char* s, int offset)
    {
    int l = strlen(s);
    int i;

    for (i = offset; i < l; ++i)
        {
        OutputToLcd (s[i]);
        }
    for (i = 0; i < offset; ++i)
        {
        OutputToLcd (s[i]);
        }

    }

Lots of ways to get this result, with different speed/space tradeoffs.

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