How to replace multiple spaces with one space?

Question

Well, I'm looking for a function that cuts a few space characters ' 'in a string.

For example, for a line s:

s="hello__________world____!"

Function should return "hello_world_!"

In python, we can do this via regexp just like:

re.sub("\s+", " ", s);

Answer 1

A version that modifies the string in place will run it on a copy if the original must be saved:

void compress_spaces(char *str)
{
    char *dst = str;

    for (; *str; ++str) {
        *dst++ = *str;

        if (isspace(*str)) {
            do ++str; 

            while (isspace(*str));

            --str;
        }
    }

    *dst = 0;
}

Answer 2

There is no such function in the standard C library. You need to write a function for this or use a third-party library.

. . , .

void
simplifyWhitespace(char * dst, const char * src)
{
    for (; *src; ++dst, ++src) {
        *dst = *src;
        if (isspace(*src))
            while (isspace(*(src + 1)))
                ++src;
    }

    *dst = '\0';
}

Answer 3

void remove_more_than_one_space(char *dest, char *src)
{
    int i, y;
    assert(dest && src);
    for(i=0, y=0; src[i] != '\0'; i++, y++) {
        if(src[i] == ' ' && src[i+1] == ' ') {
            /* let skip this copy and reduce the y index*/
            y--;
            continue;
        }
        /* copy normally */
        dest[y] = src[i];
    }
    dest[y] = '\0';
}
int main()
{
    char src[] = "Hello   World   ! !!   !";
    char dest[strlen(src) + 1];
    remove_more_than_one_space(dest, src);

    printf("%s\n", dest);
}

, , .

Answer 4

#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main()
{
    char word[100];
    gets(word);
    //the word has more than a single space in between the words
    int i=0,l,j;
    l=strlen(word);
    for (i=0;i<l;i++)
    {
        if(word[i]==' '&&word[i+1]==' ')
        {
            for(j=i+1;j<l;j++)
            word[j]=word[j+1];
        }
    }
    puts(word);
    return 0;
}

, . , - , , .

Answer 5

C, . " C", .

:

#include <stdio.h>

int main()
{
    /* Set two integers:
       c is the character being assessed,
       lastspace is 1 if the lastcharacter was a space*/
    int c, lastspace;
    lastspace = 0;

    /* This while loop will exit if the character is EOF

       The first "If block" is true if the character is not a space,
       and just prints the character
       It also tells us that the lastcharacter was not a space

       The else block will run if the character is a space

       Then the second IF block will run if the last character
       was not also a space (and will print just one space) */

    while((c = getchar()) != EOF){
        if (c != ' '){
            putchar(c);
            lastspace = 0;
        }
        else {
            if (lastspace != 1)
                    putchar(c);
            lastspace = 1;
        }
    }

    return 0;
}

Hope this helps! In addition, I know well that this code may not be optimized, but it should be simple for a beginner, as I understand!

Thanks Phil

Answer 6

another way to do this is to print only the first occurrence of space before the next character appears, here is my solution for brute force.

#include<stdio.h>
typedef int bool;
#define True  1
#define False 0
int main()
{
        int t;
        bool flag = False;

        while ((t = getchar()) != EOF)
                if (t == ' ' && !flag)
                {
                        putchar(' ');
                        flag = True; // flag is true for the first occurence of space
                }

                else if(t == ' '&& flag)
                        continue;
                else
                {
                        putchar(t);
                        flag = False;
                }

        return 0;
}

hope this helps.