replacing string with character in C

Question

The code takes user input(html tag)

ex:
<p> The content is &nbsp; text only &nbsp; inside tag </p>

gets(str);

Task is to replace all   occurences with a newline("\n")

while((ptrch=strstr(str, "&nbsp;")!=NULL)
{
  memcpy(ptrch, "\n", 1);
}

printf("%s", str);

The code above replaces only first character with \n.

Query is how to replace entire   with \n or how to set rest of nbsp; to something like empty character constant without terminating string with null pointer('\0').

just a suggestion ..don't use gets() .. use fgets instead — sukhvir
– sukhvir, Commented Oct 28, 2013 at 8:35

user823738 · Accepted Answer · 2013-10-29 08:03:57Z

1

You're almost there. Now just use memmove to move the memory left to the new line.

char str[255];
char* ptrchr;
char* end;

gets(str); // DANGEROUS! consider using fgets instead
end = (str + strlen(str));

while( (ptrch=strstr(str, "&nbsp;")) != NULL)
{
    memcpy(ptrch, "\n", 1);
    memmove(ptrch + 1, ptrch + sizeof("&nbsp;") - 1, end-ptrchr);
}

printf("%s", str);

edited Oct 29, 2013 at 8:03

answered Oct 28, 2013 at 8:31

user823738

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8 Comments

user1502952 Over a year ago

Sorry could you please specify the parameters also

aragaer Over a year ago

This could be optimized somewhat by moving not everything but only up to next  . Then you move from second to third by 10 characters etc.

aragaer Over a year ago

Why strcpy is going to work? We're dealing with overlapping memory here.

user823738 Over a year ago

@aragaer No. Overlapping may be only when you move memory to right, not to left.

aragaer Over a year ago

@Zaffy doesn't it depend on implementation?

|

aragaer · Accepted Answer · 2013-10-28 08:33:54Z

1

Instead of memcpy you could directly set the character to '\n': *ptchr = '\n'; And after that use memmove to move the rest of the line left - you replaced 6 characters with 1, so you have to move the line by 5 characters.

answered Oct 28, 2013 at 8:33

aragaer

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Comments

kunal · Accepted Answer · 2013-10-28 09:21:24Z

0

Code

    char * ptrch = NULL;
    int len =0;
    while(NULL != (ptrch=strstr(str, "&nbsp;")))
    {
      len = strlen(str) - strlen(ptrch);
      memcpy(&str[len],"\n",1);
      memmove(&str[len+1],&str[len+strlen("&nbsp;")],strlen(ptrch ));   
    }

answered Oct 28, 2013 at 9:21

kunal

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