Program is removing spaces in string uninteded

Question

I am a beginner programmer taking a class and I cannot get my output strings to print with spaces in between words. Here is my code below. It is supposed to take a string that I input and either change to all caps or all lower case as I specify when I run the program. If I put in MY CODE DOES NOT WORK, it outputs mycodedoesnotwork. Why is it removing the spaces?

 1 #include <stdio.h>
 2 #include <assert.h>
 3 #include <stdlib.h>
 4 #include <string.h>
 5
 6
 7 int shout(char * msgIn, char * msgOut) {
 8
 9         if (!msgIn || !msgOut)
 10                 return -1;
 11         while (*msgIn != '\0') {
 12                 if ('a' <= *msgIn && *msgIn <= 'z')
 13                         *msgOut = *msgIn + ('A' - 'a');
 14                 else
 15                         *msgOut = *msgIn;
 16                 msgIn++;
 17                 msgOut++;
 18         }
 19         *msgOut = '\0';
 20
 21         return 0;
 22 }
 23
 24
 25 int whisper(char const * msgIn, char * msgOut) {
 26         if (!msgIn || !msgOut)
 27                 return -1;
 28         while (*msgIn != '\0') {
 29                 if ('A' <= *msgIn && *msgIn <= 'Z')
 30                         *msgOut = *msgIn + ('a' - 'A');
 31                 else
 32                         *msgOut = *msgIn;
 33                 msgIn++;
 34                 msgOut++;
 35         }
 36         *msgOut = '\0';
 37         return 0;
 38 }
 39
 40 int main(int argc, char ** argv) {
 41         char in[128], out[128];
 42         int i;
 43         for (i = 1; i < argc; i++) {
 44                 if (strcmp("-w", argv[i]) == 0)
 45                         while (scanf("%s", in) != EOF) {
 46                                 whisper(in, out);
 47                                 printf("%s", out);
 48                         }
 49                 else if (strcmp("-s", argv[i]) == 0)
 50                         while (scanf("%s", in) != EOF) {
 51                                 shout(in, out);
 52                                 printf("%s", out);
 53                         }
 54         }
 55         printf("\n");
 56         return 0;
 57 }

~

I figured it would help so someone could specify which line they were referring to but I'll note your request. — David Webster
– David Webster, Commented Oct 4, 2013 at 10:19

Oliver Matthews · Accepted Answer · 2013-10-04 10:21:56Z

1

The scanf calls are reading in just the words (no spaces) and you are not adding spaces back in when you output your strings.

If you don't mind a trailing space, just change lines 47 and 52 to printf("%s ", out)

answered Oct 4, 2013 at 10:21

Oliver Matthews

7,9033 gold badges37 silver badges37 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

David Webster Over a year ago

Thanks for the fix Oliver. That will do for my assignment due later today but I will check my undestanding of scanf and redoing it with a different approach.

Gangadhar · Accepted Answer · 2013-10-04 10:22:27Z

1

while (scanf("%s", in) != EOF)==> scanf() takes input up to space and send to function

and then in next iteration again takes word after space.

You need to use fgets() instead.

answered Oct 4, 2013 at 10:22

Gangadhar

10.5k3 gold badges33 silver badges52 bronze badges

2 Comments

David Webster Over a year ago

I'll look into this. The book has not yet gone over fgets() so it is implied that it must want it done with scanf. I'll look into this. Thank you for the tip.

Gangadhar Over a year ago

its up to you. now just see the link.there you will found implementation.

Rohan · Accepted Answer · 2013-10-04 10:23:12Z

0

It is not problem with your shout() or wisper() functions, but problem with scanf().

When you specify %s to read string, the string will terminate at any white space chars - space, tab etc.

And that will not be included in the string. So space that you enter between the strings are not stored in in variable.

You may want to think of different approach to solve that.

answered Oct 4, 2013 at 10:23

Rohan

53.5k12 gold badges95 silver badges89 bronze badges

1 Comment

David Webster Over a year ago

This is the only way the book has showed us to read strings and use them so it's my only approach. I'll look into fgets(). This book is a bit lacking. Thanks for the reply.

Federico · Accepted Answer · 2013-10-04 10:26:26Z

0

The space is a string terminator for scanf() and scanf() does not include it in the acquired string. man 3 scanf

answered Oct 4, 2013 at 10:26

Federico

3,93235 silver badges47 bronze badges

Collectives™ on Stack Overflow

Program is removing spaces in string uninteded

4 Answers 4

1 Comment

2 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

2 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related