Can I rewind a string like I can a file?

Think about this. printf, sprintf, and fprintf all work on streams, right? Just like scanf, sscanf, and fscanf work on streams?

When I use a function like rewind() or fseek() with SEEK_END, it changes where the stream position is, it changes where fprintf begins outputting, and where sscanf begins inputting.

So, since strings are streams, like files are, can I rewind a string like I can a file?

I guess I could write my string to a file and then use fscanf as a last resort, but I'm just wondering if there's an easier way. How would I go about writing a function like this myself?

Give it a go and post some code. It would be pointless to write it to a file, so don't do that!

BTW, C++ has a stringstream class.

Quote:

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Originally Posted by Babkockdood

Think about this. printf, sprintf, and fprintf all work on streams, right? Just like scanf, sscanf, and fscanf work on streams?

When I use a function like rewind() or fseek() with SEEK_END, it changes where the stream position is, it changes where fprintf begins outputting, and where sscanf begins inputting.

So, since strings are streams, like files are, can I rewind a string like I can a file?

I guess I could write my string to a file and then use fscanf as a last resort, but I'm just wondering if there's an easier way. How would I go about writing a function like this myself?

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To rewind a string all you have to do is put it back some where between where it is and the start of the string;

Code:

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char buff[1024];
char *b = buff;
int      x;
x = sprintf(b,"hello world %ld\n", (long)time(NULL));
if(x <= 0)
  return;
b += x ;
x = sprintf(b,"hello world %d\n", b - buff);
if(x <= 0)
  return;
b += x;
/*** to rewind the string pointed to by b  ***/
b = buff;
x = sprintf(b,"hello world %d\n", b - buff);
if(x <= 0)
  return;
/** will print "hello world 0\n" ***/
printf("%s\n", buff);

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