Remove extra blanks

[Registered User]

Hi experts,
I'm trying to write a program that replaces two or more consecutive
blanks in a string by a single blank.

Here's what I did:

#include <stdio.h>
#include <string.h>
#define MAX 80

int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=strlen(s);
while(i)
{
while (s[--i]!=' ' && i>0) /*Find the last space*/
;
j=i;
while (s[--j]==' ' && j>0) /*Go to the last non-space*/
; /*char before s[i]*/

if (s[j]!=' ')
j++; /*Increment j so that s[j] is a space*/

if (j<i) /*If extra spaces have been found, remove*/
while (s[i]) /*them by left shifting */
s[++j]=s[++i]; /*the characters on the right*/

i=j;
}
puts(s);

return 0;
}

The program works fine, but I have a feeling that I've made it
unnecessarily complicated.


Can anyone suggest ways on which I can improve upon the code? Is there
a better algorithm?

[CBFalconer]

Re: Remove extra blanks

Registered User wrote:

>
I'm trying to write a program that replaces two or more consecutive
blanks in a string by a single blank.
>
Here's what I did:
>
#include <stdio.h>
#include <string.h>
#define MAX 80
>
int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=strlen(s);
while(i)
{
while (s[--i]!=' ' && i>0) /*Find the last space*/
;
j=i;
while (s[--j]==' ' && j>0) /*Go to the last non-space*/
; /*char before s[i]*/
>
if (s[j]!=' ')
j++; /*Increment j so that s[j] is a space*/
>
if (j<i) /*If extra spaces have been found, remove*/
while (s[i]) /*them by left shifting */
s[++j]=s[++i]; /*the characters on the right*/
>
i=j;
}
puts(s);
>
return 0;
}
>
The program works fine, but I have a feeling that I've made it
unnecessarily complicated.
>
Can anyone suggest ways on which I can improve upon the code? Is there
a better algorithm?

Try this. Notice the absence of string buffers. Should work until
you get over 32767 consecutive blanks.

#include <stdio.h>
int main(void)
{
int blanks, ch;

blanks = 0;
while (EOF != (ch = getchar())) {
if (' ' == ch) {
++blanks;
if (1 == blanks) putchar(' ');
}
else {
putchar(ch);
blanks = 0;
}
}
return 0;
}

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>

[Richard]

Re: Remove extra blanks

"Registered User" <invalidinvalid invalid@gmail.c omwrites:

Hi experts,
I'm trying to write a program that replaces two or more consecutive
blanks in a string by a single blank.
>
Here's what I did:
>
#include <stdio.h>
#include <string.h>
#define MAX 80
>
int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=strlen(s);
while(i)
{
while (s[--i]!=' ' && i>0) /*Find the last space*/
;
j=i;
while (s[--j]==' ' && j>0) /*Go to the last non-space*/
; /*char before s[i]*/
>
if (s[j]!=' ')
j++; /*Increment j so that s[j] is a space*/
>
if (j<i) /*If extra spaces have been found, remove*/
while (s[i]) /*them by left shifting */
s[++j]=s[++i]; /*the characters on the right*/
>
i=j;
}
puts(s);
>
return 0;
}
>
The program works fine, but I have a feeling that I've made it
unnecessarily complicated.
>
>
Can anyone suggest ways on which I can improve upon the code? Is there
a better algorithm?
>

Much faster & efficient IMO (in most cases I would think) to
malloc a new string, copy the original one into it and then update the
original in place - no repeated shuffling.

strcpy(refCopy, refStr)
char *d=refStr; /*destination*/
char *s=refCopy; /*original string copy - source*/
while(*d++=(ch= *s++))
if(ch==' '){
while((ch=*s++) &&(ch==' ')); /*gobble up following spaces
if (!(*d++=ch)) /* store first non space */
break;
}

Not tested, but you will get the idea.


--


--

[Joe Wright]

Re: Remove extra blanks

CBFalconer wrote:

Registered User wrote:

>I'm trying to write a program that replaces two or more consecutive
>blanks in a string by a single blank.
>>
>Here's what I did:
>>
>#include <stdio.h>
>#include <string.h>
>#define MAX 80
>>
>int main()
>{
> char s[MAX];
> int i, j;
> fgets(s, MAX, stdin);
> i=strlen(s);
> while(i)
> {
> while (s[--i]!=' ' && i>0) /*Find the last space*/
> ;
> j=i;
> while (s[--j]==' ' && j>0) /*Go to the last non-space*/
> ; /*char before s[i]*/
>>
> if (s[j]!=' ')
> j++; /*Increment j so that s[j] is a space*/
>>
> if (j<i) /*If extra spaces have been found, remove*/
> while (s[i]) /*them by left shifting */
> s[++j]=s[++i]; /*the characters on the right*/
>>
> i=j;
> }
> puts(s);
>>
> return 0;
>}
>>
>The program works fine, but I have a feeling that I've made it
>unnecessaril y complicated.
>>
>Can anyone suggest ways on which I can improve upon the code? Is there
>a better algorithm?

>
Try this. Notice the absence of string buffers. Should work until
you get over 32767 consecutive blanks.
>
#include <stdio.h>
int main(void)
{
int blanks, ch;
>
blanks = 0;
while (EOF != (ch = getchar())) {
if (' ' == ch) {
++blanks;
if (1 == blanks) putchar(' ');
}
else {
putchar(ch);
blanks = 0;
}
}
return 0;
}
>

Or maybe..

#include <stdio.h>
int main(void) {
int ch, last = 0;
while ((ch = getchar()) != EOF) {
if (!(ch == ' ' && last == ch))
putchar(ch);
last = ch;
}
return 0;
}

--
Joe Wright
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

[Richard]

Re: Remove extra blanks

Joe Wright <joewwright@com cast.netwrites:

CBFalconer wrote:

>Registered User wrote:

>>I'm trying to write a program that replaces two or more consecutive
>>blanks in a string by a single blank.
>>>
>>Here's what I did:
>>>
>>#include <stdio.h>
>>#include <string.h>
>>#define MAX 80
>>>
>>int main()
>>{
>> char s[MAX];
>> int i, j;
>> fgets(s, MAX, stdin);
>> i=strlen(s);
>> while(i)
>> {
>> while (s[--i]!=' ' && i>0) /*Find the last space*/
>> ;
>> j=i;
>> while (s[--j]==' ' && j>0) /*Go to the last non-space*/
>> ; /*char before s[i]*/
>>>
>> if (s[j]!=' ')
>> j++; /*Increment j so that s[j] is a space*/
>>>
>> if (j<i) /*If extra spaces have been found, remove*/
>> while (s[i]) /*them by left shifting */
>> s[++j]=s[++i]; /*the characters on the right*/
>>>
>> i=j;
>> }
>> puts(s);
>>>
>> return 0;
>>}
>>>
>>The program works fine, but I have a feeling that I've made it
>>unnecessari ly complicated.
>>>
>>Can anyone suggest ways on which I can improve upon the code? Is there
>>a better algorithm?

>Try this. Notice the absence of string buffers. Should work until
>you get over 32767 consecutive blanks.
>#include <stdio.h>
>int main(void)
>{
> int blanks, ch;
> blanks = 0;
> while (EOF != (ch = getchar())) {
> if (' ' == ch) {
> ++blanks;
> if (1 == blanks) putchar(' ');
> }
> else {
> putchar(ch);
> blanks = 0;
> }
> }
> return 0;
>}
>>

Or maybe..
>
#include <stdio.h>
int main(void) {
int ch, last = 0;
while ((ch = getchar()) != EOF) {
if (!(ch == ' ' && last == ch))
putchar(ch);
last = ch;
}
return 0;
}

The problem is that I think the OP was only using fgets to get a sample
string - it is therefore not the excercise to simplify the algorithm
using getchar() or whatever.

His spec was to remove excess spaces from a string.

I could be wrong : if not, see other post.

--

[Registered User]

Re: Remove extra blanks


Richard wrote:

Joe Wright <joewwright@com cast.netwrites:
>

CBFalconer wrote:

Registered User wrote:
>I'm trying to write a program that replaces two or more consecutive
>blanks in a string by a single blank.
>>
>Here's what I did:
>>
>#include <stdio.h>
>#include <string.h>
>#define MAX 80
>>
>int main()
>{
> char s[MAX];
> int i, j;
> fgets(s, MAX, stdin);
> i=strlen(s);
> while(i)
> {
> while (s[--i]!=' ' && i>0) /*Find the last space*/
> ;
> j=i;
> while (s[--j]==' ' && j>0) /*Go to the last non-space*/
> ; /*char before s[i]*/
>>
> if (s[j]!=' ')
> j++; /*Increment j so that s[j] is a space*/
>>
> if (j<i) /*If extra spaces have been found, remove*/
> while (s[i]) /*them by left shifting */
> s[++j]=s[++i]; /*the characters on the right*/
>>
> i=j;
> }
> puts(s);
>>
> return 0;
>}
>>
>The program works fine, but I have a feeling that I've made it
>unnecessaril y complicated.
>>
>Can anyone suggest ways on which I can improve upon the code? Is there
>a better algorithm?
Try this. Notice the absence of string buffers. Should work until
you get over 32767 consecutive blanks.
#include <stdio.h>
int main(void)
{
int blanks, ch;
blanks = 0;
while (EOF != (ch = getchar())) {
if (' ' == ch) {
++blanks;
if (1 == blanks) putchar(' ');
}
else {
putchar(ch);
blanks = 0;
}
}
return 0;
}
>

Or maybe..

#include <stdio.h>
int main(void) {
int ch, last = 0;
while ((ch = getchar()) != EOF) {
if (!(ch == ' ' && last == ch))
putchar(ch);
last = ch;
}
return 0;
}

>
The problem is that I think the OP was only using fgets to get a sample
string - it is therefore not the excercise to simplify the algorithm
using getchar() or whatever.
>
His spec was to remove excess spaces from a string.
>

Yes, that's what I want to do: remove excess spaces from a given string.

[Andrew Poelstra]

Re: Remove extra blanks

On Sun, 2006-10-15 at 04:22 -0700, Registered User wrote:

Hi experts,
I'm trying to write a program that replaces two or more consecutive
blanks in a string by a single blank.
>
Here's what I did:
>
#include <stdio.h>
#include <string.h>
#define MAX 80
>
int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=strlen(s);
while(i)
{
while (s[--i]!=' ' && i>0) /*Find the last space*/
;
j=i;
while (s[--j]==' ' && j>0) /*Go to the last non-space*/
; /*char before s[i]*/
>
if (s[j]!=' ')
j++; /*Increment j so that s[j] is a space*/
>
if (j<i) /*If extra spaces have been found, remove*/
while (s[i]) /*them by left shifting */
s[++j]=s[++i]; /*the characters on the right*/
>
i=j;
}
puts(s);
>
return 0;
}
>
The program works fine, but I have a feeling that I've made it
unnecessarily complicated.
>

Well, use spaces instead of tabs. I've replaced yours with two-space
indents. (On USENET, tabs can be filtered out or displayed incorrectly.)

>
Can anyone suggest ways on which I can improve upon the code? Is there
a better algorithm?
>

It'd be better to use two strings, an input and an output. That way, you
can make a function that accepts string literals. (String literals are
non-mutable, in case you didn't know.)

If you use two strings, you can simply copy each character until you hit
a space. Then, copy a space, skip to the next non-whitespace character,
and continue as you were.

--
Andrew Poelstra <http://www.wpsoftware. net/projects/>

[lovecreatesbea...@gmail.com]

Re: Remove extra blanks


Registered User wrote:

Hi experts,
I'm trying to write a program that replaces two or more consecutive
blanks in a string by a single blank.
>
Here's what I did:
>
#include <stdio.h>
#include <string.h>
#define MAX 80
>
int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=strlen(s);
while(i)
{
while (s[--i]!=' ' && i>0) /*Find the last space*/
;
j=i;
while (s[--j]==' ' && j>0) /*Go to the last non-space*/
; /*char before s[i]*/
>
if (s[j]!=' ')
j++; /*Increment j so that s[j] is a space*/
>
if (j<i) /*If extra spaces have been found, remove*/
while (s[i]) /*them by left shifting */
s[++j]=s[++i]; /*the characters on the right*/
>
i=j;
}
puts(s);
>
return 0;
}
>
The program works fine, but I have a feeling that I've made it
unnecessarily complicated.
>
>
Can anyone suggest ways on which I can improve upon the code? Is there
a better algorithm?

just as an alternative,

/*removes extra blanks from a string, replaces two or more consecutive
blanks in a string by a single space.*/
int sglspc(char *s){
int n;
char *p, *p2;

n = 0;
p = s;

while (*p){
if (*p == ' ' && *(p + 1) == *p){
n++;
p2 = p;

while (*p2){
*p2 = *(p2 + 1);
p2++;
}
} else
p++;
}

return n;
}

#include <stdio.h>
#include <string.h>
int main(void){
char s[] = " hello world ";
int n;

printf("%s, %d\n", s, strlen(s));
n = sglspc(s);
printf("%s, %d, (-%d)\n", s, strlen(s), n);

return 0;
}

$ a.out
hello world , 27
hello world , 13, (-14)

$

[Richard]

Re: Remove extra blanks

Richard <rgrdev@gmail.c omwrites:

"Registered User" <invalidinvalid invalid@gmail.c omwrites:
>

>Hi experts,
>I'm trying to write a program that replaces two or more consecutive
>blanks in a string by a single blank.
>>
>Here's what I did:
>>
>#include <stdio.h>
>#include <string.h>
>#define MAX 80
>>
>int main()
>{
> char s[MAX];
> int i, j;
> fgets(s, MAX, stdin);
> i=strlen(s);
> while(i)
> {
> while (s[--i]!=' ' && i>0) /*Find the last space*/
> ;
> j=i;
> while (s[--j]==' ' && j>0) /*Go to the last non-space*/
> ; /*char before s[i]*/
>>
> if (s[j]!=' ')
> j++; /*Increment j so that s[j] is a space*/
>>
> if (j<i) /*If extra spaces have been found, remove*/
> while (s[i]) /*them by left shifting */
> s[++j]=s[++i]; /*the characters on the right*/
>>
> i=j;
> }
> puts(s);
>>
> return 0;
>}
>>
>The program works fine, but I have a feeling that I've made it
>unnecessaril y complicated.
>>
>>
>Can anyone suggest ways on which I can improve upon the code? Is there
>a better algorithm?
>>

>
Much faster & efficient IMO (in most cases I would think) to
malloc a new string, copy the original one into it and then update the
original in place - no repeated shuffling.
>
strcpy(refCopy, refStr)
char *d=refStr; /*destination*/
char *s=refCopy; /*original string copy - source*/
while(*d++=(ch= *s++))
if(ch==' '){
while((ch=*s++) &&(ch==' ')); /*gobble up following spaces
if (!(*d++=ch)) /* store first non space */
break;
}
>
Not tested, but you will get the idea.
>

Idiocy alert : you dont even need the copy thus saving fannying around
with mallocs etc. Just set s to be d. This is fine since s is always
the same or, after the first double space, ahead of the destination pointer.

Whoops.


--

[jacob navia]

Re: Remove extra blanks

The strtrim function from the lcc-win32 compiler looks like this:
#include <ctype.h>
int strtrim(char *str)
{
char *src = str,*dst = str,*start = str;

while (isspace(*src)) // Skip leading spaces
src++;
do {
// Copy non space chars
while (*src && !isspace(*src))
*dst++ = *src++;
// Here we have either zero or a space
if (*src) {
*dst++ = *src++; // Copy first space
while (isspace(*src) && // Skip the rest
*src != '\n' && *src != '\r')
src++;
}
} while (*src);
// If the last character before a newline is space, delete it.
if (dst != start && isspace(dst[-1]) && dst[-1] != '\n')
dst--;
*dst = 0;
return dst - src;
}

[free4trample@yahoo.com]

Re: Remove extra blanks

This si as simple as it gets, i think...
Problem with this code is that it adds a SPACE character at the end of
a file.

=============== =====Start paste========== =============
#include<stdio. h>
#include<string .h>
#define MAX_LINE_LENGHT H 200
#define MAX_FN_LENGTH 20

int main(void){
char filein[MAX_FN_LENGTH], fileout[MAX_FN_LENGTH],
s1[MAX_LINE_LENGHT H], *s2;
FILE *ff1, *ff2;

printf("Enter input file: ");
scanf("%s",file in);
printf("\nEnter output file: ");
scanf("%s",file out);
ff1=fopen(filei n,"r");
ff2=fopen(fileo ut,"w");

while(!feof(ff1 )){
fgets(s1,MAX_LI NE_LENGHTH,ff1) ;
s2=strtok(s1," ");
fprintf(ff2,"%s ",s2);
while((s2=strto k('\0'," "))!=NULL){
if(s2[strlen(s2)-1]!='\n')
fprintf(ff2,"%s ",s2);
else
fprintf(ff2,"%s ",s2);
}
}

fclose(ff1);
fclose(ff2);
return 0;
}
=============== ====End Paste========== =======

[Registered User]

Re: Remove extra blanks

Richard wrote:

Richard <rgrdev@gmail.c omwrites:
>

"Registered User" <invalidinvalid invalid@gmail.c omwrites:

Hi experts,
I'm trying to write a program that replaces two or more consecutive
blanks in a string by a single blank.
>
Here's what I did:
>
#include <stdio.h>
#include <string.h>
#define MAX 80
>
int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=strlen(s);
while(i)
{
while (s[--i]!=' ' && i>0) /*Find the last space*/
;
j=i;
while (s[--j]==' ' && j>0) /*Go to the last non-space*/
; /*char before s[i]*/
>
if (s[j]!=' ')
j++; /*Increment j so that s[j] is a space*/
>
if (j<i) /*If extra spaces have been found, remove*/
while (s[i]) /*them by left shifting */
s[++j]=s[++i]; /*the characters on the right*/
>
i=j;
}
puts(s);
>
return 0;
}
>
The program works fine, but I have a feeling that I've made it
unnecessarily complicated.
>
>
Can anyone suggest ways on which I can improve upon the code? Is there
a better algorithm?
>

Much faster & efficient IMO (in most cases I would think) to
malloc a new string, copy the original one into it and then update the
original in place - no repeated shuffling.

strcpy(refCopy, refStr)
char *d=refStr; /*destination*/
char *s=refCopy; /*original string copy - source*/
while(*d++=(ch= *s++))
if(ch==' '){
while((ch=*s++) &&(ch==' ')); /*gobble up following spaces
if (!(*d++=ch)) /* store first non space */
break;
}

Not tested, but you will get the idea.

Thanks for the idea, Richard. I've implemented something similar:

#include <stdio.h>
#define MAX 80
int main()
{
char s[MAX];
int i, j;
fgets(s, MAX, stdin);
i=j=0;
while(s[i++]=s[j++])
{
if (s[i-1]==' ') /*If the last character copied was a space*/
{
while (s[j++]==' ') /*gobble up following spaces */
;
if ((s[i++]=s[j-1])=='\0')
break;
}
}
puts(s);
return 0;
}

>
Idiocy alert : you dont even need the copy thus saving fannying around
with mallocs etc. Just set s to be d. This is fine since s is always
the same or, after the first double space, ahead of the destination pointer.
>
Whoops.

Yeah, that was funny.

[free4trample@yahoo.com]

Re: Remove extra blanks

Actually made the body of my lst post too complex, here is the bug
free, simpler version.

=============== ====Start paste========== =====
#include<stdio. h>
#include<string .h>
#define MAX_LINE_LENGHT H 200
#define MAX_FN_LENGTH 20

int main(void){
char filein[MAX_FN_LENGTH], fileout[MAX_FN_LENGTH],
s1[MAX_LINE_LENGHT H], *s2;
FILE *ff1, *ff2;

printf("Enter input file: ");
scanf("%s",file in);
printf("\nEnter output file: ");
scanf("%s",file out);
ff1=fopen(filei n,"r");
ff2=fopen(fileo ut,"w");

while(!feof(ff1 )){
fgets(s1,MAX_LI NE_LENGHTH,ff1) ;
s2=strtok(s1," ");
fprintf(ff2,"%s ",s2);
while((s2=strto k('\0'," "))!=NULL){
fprintf(ff2," %s",s2);
}
}

fclose(ff1);
fclose(ff2);
return 0;
}
=============== ==End Paste========== ==========

This one has no bugs either.

[Richard Heathfield]

Re: Remove extra blanks

free4trample@ya hoo.com said:

This si as simple as it gets, i think...
Problem with this code is that it adds a SPACE character at the end of
a file.
>
=============== =====Start paste========== =============
#include<stdio. h>
#include<string .h>
#define MAX_LINE_LENGHT H 200
#define MAX_FN_LENGTH 20
>
int main(void){
char filein[MAX_FN_LENGTH], fileout[MAX_FN_LENGTH],
s1[MAX_LINE_LENGHT H], *s2;
FILE *ff1, *ff2;
>
printf("Enter input file: ");
scanf("%s",file in);

ThisIsWhatIType InResponseToYou rInputRequest. That's mischievous, but not
malicious. If you use "%s" with scanf, you open yourself up to malice as
well as mischief.

printf("\nEnter output file: ");
scanf("%s",file out);

Same applies.

ff1=fopen(filei n,"r");
ff2=fopen(fileo ut,"w");

What if these operations fail?

>
while(!feof(ff1 )){
fgets(s1,MAX_LI NE_LENGHTH,ff1) ;

This code will process the last line twice. Instead, use:

while(fgets(s1, MAX_LINE_LENGHT H, ff1) != NULL)
{

or better still:

while(fgets(s1, sizeof s1, ff1) != NULL)
{

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)

[Thad Smith]

Re: Remove extra blanks

lovecreatesbea. ..@gmail.com wrote:

Registered User wrote:
>

>>Hi experts,
>>I'm trying to write a program that replaces two or more consecutive
>>blanks in a string by a single blank.

>
just as an alternative,
>
/*removes extra blanks from a string, replaces two or more consecutive
blanks in a string by a single space.*/
int sglspc(char *s){
int n;
char *p, *p2;
>
n = 0;
p = s;
>
while (*p){
if (*p == ' ' && *(p + 1) == *p){
n++;
p2 = p;
>
while (*p2){
*p2 = *(p2 + 1);
p2++;
}
} else
p++;
}
>
return n;
}
>
#include <stdio.h>
#include <string.h>
int main(void){
char s[] = " hello world ";
int n;
>
printf("%s, %d\n", s, strlen(s));
n = sglspc(s);
printf("%s, %d, (-%d)\n", s, strlen(s), n);
>
return 0;
}

int sglspc(char *s){
int n = 0;
char *d = s;
while (*d++ = *s)
while (*s++ == ' ' && *s == ' ') n++;
return n;
}

As part of a real program, it would be longer.

--
Thad