removing spaces in a string

[camel-man]

// remove specified number of characters starting at

// a specified index.

// first int is starting index, second is count

void removeString(char *, int, int);

only using pointers and no brackets in the program.

for example removestrng(char* test, 4, 6)

text = "the wrong son" you move over 4 spaces to where the 'w' starts then remove 6 spaces out so the string would be "the son" in int main.

i know how to get the characters where i want them I just do not know what kind of strategy to be used when deleting the spaces.
P.S. this is all being done in a function nothing can be declared in main.

[CommonTater]

Read This .... C Board - Announcements in Forum : General Programming Boards

Make an effort, post your code if you get stuck... otherwise...

[camel-man]

i havnt written any code im still writing pseudo code on paper

[Adak]

I think of it as a two part process, using two for loops, in the (I call it snip, because remove is a keyword), snip() function.

First part is the overwrite of the char's from the start, to the length. The length serves as the offset of how far each char is moved over.

Second part is the shift of the rest of the string, from the point where the last char was shifted, through until you reach the end of the string (including the end of string char).

Hopefully, you've worked with pointers on strings before, at least a little. You'll find it challenging, otherwise. Remember that you can add an int to a pointer, no problem (and you should here), but you can't add two pointers. You can subtract two pointers, but it's not needed here.

[nonoob]

Well you can't really delete characters. What you do is move characters into the positions formerly occupied.

the wrong son
          |||
          ///
         ///
        ///
       ///
      ///
     ///
    ///
    |||
the son

So your task is to find out which is the first character to move... Starting with the one at 4+6, and move it to destination 4.
Since you are not allowed indexing (square brackets), you need to keep a source pointer and destination pointer. Then don't forget to put a trailing null to signal the end of the string.

[camel-man]

void removestrng(char *st1,int start,int numR)
{

int c1=0, c2=0, p=0;


while(p<start)
{c1++;
*st1++;
p++;
}


c2=c1+numR;


printf("c1=%i\n", c1);
printf("c2=%i\n", c2);
printf("*st1=%c\n", *st1);
printf("start=%i\n", start);







}

thats what I have so far just to see where my pointers and counters are at now I am stuck at how to shift the letters behind NULL because that is the way Im pretty sure you have to go about deleting the characters

[quzah]

String functions typically stop when they encounter a null character. So all you have to do is put the null where you want the end of the string to be. Anything beyond that will be ignored.


Quzah.

[camel-man]

question is how do I go about that involving random numbers being entered into main I cannot just hardcode it when someone else is using the program. would it be wise to use a while loop ?

[Adak]

I wouldn't worry about random numbers, etc., just now. Focus on your called function. What the actual start and length of the chars are that gets removed, don't matter yet.

That's one of the best things about functions - they encapsulate the logic for one part of the work to be done, into one certain area of the code.

I wouldn't increment *st1. Instead, leave st1 as is, and simply "walk" through the chars, by using the loop counter. *(st1 + i) kind of expressions is what I would expect here.

A while loop is OK, and perhaps more intuitive for the second loop, which will shift the remaining char's over to the left, by the length of the second int you pass into the function.

The first loop should be a for loop imo, since it's start and ending point, is already exactly given by the parameters.

[camel-man]

ok so a for loop such as this for(;*st1<start;*st1++)? i dont think I need to initialize *st1 in the beginning of the for loop since it is already given in main.

[Adak]

ok so a for loop such as this for(;*st1<start;*st1++)? i dont think I need to initialize *st1 in the beginning of the for loop since it is already given in main.

Nope! Don't change *st1.At least, the way I do it (certainly not the only way), I use a loop iterator:

for(i=start;i<start + ?;i++)

I'll bet you can figure out what goes in the ? spot.

[camel-man]

once i walk through my chars how exactly can you move the null to a certain index. is it through an assignment operator? or will I have to use some kind of for loop and pointer to convert the null index to specified index.

[quzah]

It's just a number. Assign it the same way you assign any number.


Quzah.

[camel-man]

sweet thanks so much