function SpacePlug takes a pointer to string and a another char as arguments.

Question

void SpacePlug(char *StringPtr, char Ch)
{
    int i = 0;
    while (*(StringPtr + i)!= '\0')
    {
        if (*(StringPtr + i)== ' ')
        {
            *(StringPtr + i ) = '^^';
            printf("%c",*(StringPtr + i));
        }
        i++;
    }
}
int main()
{
    char a[]= "Alton Tait";
    SpacePlug(a,);
}

Function is to replace each space in the string with the character .In main, use SpacePlug i want to replace the space between alton tait with ^^ so it should be alton^^tait thats what i come up with i cant i would like to know where i went wrong. thank you

This looks like C (with a syntax error). Why did you add the C++ tag? — too honest for this site, Apr 16 '17 at 18:00
Tags are not to attract maximum attention, but sort questions! Please follow site rules, read [ask]. C and C++ are **different** languages. — too honest for this site, Apr 16 '17 at 19:00

score 0 · Answer 1 · edited May 23 '17 at 12:02

0

'^^' is not a character. It is a multi-character constant, which is not portable.

Your code is good for a single-character replacements, i.e.

SpacePlug(a, '^');

You also need to move printing out of the if:

int i = 0;
while (*(StringPtr + i)!= '\0')
{
    if (*(StringPtr + i)== ' ')
    {
        *(StringPtr + i ) = '^';
    }
    printf("%c", *(StringPtr + i));
    i++;
}

Demo.

To make replacements for multiple characters you need an entirely different approach:

Pass char* for the replacement
Make sure the string has enough space to expand for the extra characters
Do the replacement in two passes
Compute the total length after replacement in the first pass
Starting from the back, perform replacements as you go, using the same space.

edited May 23 '17 at 12:02

Community

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answered Apr 16 '17 at 18:02

Sergey Kalinichenko

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Sorry about the double character '^^' i only need it to replace with one thank for your help really appreciate . – A.Tait Apr 16 '17 at 18:56
wheneve i run it, its only printing out ^ its not printing out Alton^tait. – A.Tait Apr 16 '17 at 19:13

neoland · Answer 2 · 2017-04-16T19:23:55.267

This is the output i get when i try to compile your code using gcc:

In function 'SpacePlug':
8:33: warning: multi-character character constant [-Wmultichar]
             *(StringPtr + i ) = '^^';
                                 ^
8:33: warning: overflow in implicit constant conversion [-Woverflow]
 In function 'main':
17:17: error: expected expression before ')' token
     SpacePlug(a,);

you should hace included the error report in the question, so it's easier to see what's going on.

You've got a few problems on your code:

"^^" is not a character, but a string with 2 characters. '^' is a character. That's the reason for the "multi-charater" error
You're not using "Ch" inside SpacePlug. The replacing character is hardcoded. I'ts always '^^', which doesn't exist.
The function is not properly called in main. It's missing a parameter.

Now for the solution. What i understood is that "SpacePlug" tries to find all spaces inside a string, the first parameter, and replace them with a character, which is the second parameter. The following code will work just fine for that:

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

void SpacePlug(char *StringPtr, char Ch, char *newString)
{   
    for (int i = 0; i < strlen(StringPtr); i++)
    {
        if (StringPtr[i] == ' ')
        {
            newString[i] = Ch;
        }
        else
        {
            newString[i] = StringPtr[i];
        }
    }
}
int main()
{
    char *a = "Alton Tait";
    char replace = '^';
    char *newString = (char *)malloc(strlen(a) + 1); // the +1 is for the null terminator
    SpacePlug(a, replace, newString);
    printf("%s\n", newString);

    free(newString);
}

Cheers.

This code fails to NULL terminate `newString`. The allocation also needs to be larger to account for the NULL. — Blastfurnace, Apr 16 '17 at 19:03
There, i edited it so a new string is taken as a parameter instead of creating it inside function. I initialize the memory space and then destroy it before leaving. Hope it compiles this time. — neoland, Apr 16 '17 at 19:24

function SpacePlug takes a pointer to string and a another char as arguments.

2 Answers2