Thread: Function to replace multiple spaces from a string

Hello,

I need a function to replace multiple spaces with only one.
I wrote this one but if it happens that the string starts with one or more spaces then the function will leave one there, like in this example:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>


void replace_spaces(char *s)
{
    char *p = s;
    while (*s != '\0')
    {
        while (isspace(*s) && isspace(*(s + 1)))
            s++;
       *p++ = *s++;
    }

    *p = '\0';
}


int main(void)
{
    char input[] = "        aaaa      bbbb   ";
    replace_spaces(input);
    puts(input);
    return EXIT_SUCCESS;
}

I'm aware of the fact that there are multiple ways to remove the first character of a string but I'd like to do this in the replace_spaces function instead of using something like memmove/strlen

It is interesting that the code becomes more complex if you think of this as a process with a special condition, rather than a series of processes, i.e., first, skip leading spaces and second, skip multiple spaces.

Originally Posted by Salem

Use another loop to skip leading spaces.

Originally Posted by christophergray

It is interesting that the code becomes more complex if you think of this as a process with a special condition, rather than a series of processes, i.e., first, skip leading spaces and second, skip multiple spaces.

Do you mean something like this?

Code:

void replace_spaces(char *s)
{
    char *p = s;


    while(isspace(*s))
    {
        s++;
    }
    while (*s != '\0')
    {
        while (isspace(*s) && isspace(*(s + 1)))
            s++;
       *p++ = *s++;
    }
  
    *p = '\0';
}

Originally Posted by SillyStudent

Do you mean something like this?

Code:

    while(isspace(*s))
    {
        s++;
    }

Exactly that, yes.