Thread: Remove a char

Im trying to remove a space from an array and for whatever reason
I get the string doubled when I call the function.
In the function itself I have the right result.

Code:

#include <iostream>
using namespace std;

void DelChar(char *src)
{
    char buf[260];
    int i =0;
    while (*(src) != '\0')
    {
        if (*(src) != ' ')
        {
            buf[i] = *(src);
            i++;
        }
        src++;
    }
    buf[i] = '\0';
    strcpy(src,buf);
    cout << "-> " << src << endl;
    return;
}

int main()
{
    char text[260] = "he llo";

    DelChar(text);
    cout << text << endl;

    return 0;
}

So which language are you programming in?

You posted C++ code in the C forum.

But you're also using messy C-style char arrays rather than std::string.

> I get the string doubled when I call the function.
Would that have anything to do with printing it twice?
Lines 19 and 28

I use C code most of the time in C++ code because there are C functions that I prefer to their C++ version.

Nah, on line 19 I get the correct result and on 28 i get it doubled with the old and the new array.

You don't actually need an extra char buffer. You can just re use src.

Code:

void DelChar(char *src)
{
    int i = 0;

    while (*(src) != '\0')
    {
        if (*(src) != ' ')

        {
            src[i] = *(src);

            i++;
        }
        src++;
    }
    src[i] = '\0';

    cout << "-> " << src << endl;
    return;
}

I haven't tested it but it should look like that.

C and C++ are two distinct languages and should be treated as such. Avoid writing pure C code in C++ unless there is a good reason to do so. If you don't know enough C++ to use the std:string and other nice utilities then program in C, and compile with a C compiler.

EDIT: Why in God's good name would you use C-style string manipulation in C++ is beyond me, when std has a lot of user friendlier string manipulation utilities.

You are getting double because you are passing src which now points to '\0' after "he llo" when you pass it to strcpy which will result to "he llohello".

@mnd22 Thank you, you are right it should work without extra buffer.
Its not working for the moment but im tryting to find out why.
"passing src which now points to '\0' after "he llo" when you pass it to strcpy" exactly, I see it now.

@claudiu They are not two distinct languages otherwise why can you use C in C++?
I prefer cout to printf for example. Also C to C++ is like WinAPI to MFC, you see more whats happening in C then in C++.

@aleris Thank you, very clear explanation.

@mnd22 The problem with this solution is that src[i] gets incremented two times each time.
Once because of i++ and again because of src++.
Here is the solution:

Code:

        if (*(src) != ' ')
        {
            src[i] = *(src);
        }
        else i--;

:-)

Originally Posted by Ducky

@mnd22 Thank you, you are right it should work without extra buffer.
Its not working for the moment but im tryting to find out why.
"passing src which now points to '\0' after "he llo" when you pass it to strcpy" exactly, I see it now.

@claudiu They are not two distinct languages otherwise why can you use C in C++?
I prefer cout to printf for example. Also C to C++ is like WinAPI to MFC, you see more whats happening in C then in C++.

You are dead wrong I am afraid. You are making the costly mistake of learning C++ from the perspective of a C developer rather than as a new language. This is a mistake that C developers often make.

> @claudiu They are not two distinct languages otherwise why can you use C in C++?
No you're wrong.
They share a common heritage, but you can't take EVERY valid C program and immediately compile it as a valid C++ program.

For example, I can do
int class;
in C, and it all works just peachy.
But it would just blow up in C++.

Read this for many more traps and pitfalls.
Incompatibilities Between ISO C and ISO C++

If you compile it with a C++ compiler, then it IS C++. Any C syntax you think you're using will be compiled according to C++ rules.

lol told you its not tested but you got the idea.

@Claudiu & Salem
Thanks I will try to lose the bad habit then.
But I hope a bit of char array manipulation cant cause much harm in a C++ code, cant it?
Or to call strcpy() and such functions in a C++ code?

There is no need for such functions in C++. std::string is infinitely superior to C strings, which are really just char arrays. The C++ standard library makes string manipulation seamless by providing a lot of built in functionality. In C you are reinventing the wheel by writing your own expensive function to perform the trivial task of removing a character.
Check string - C++ Reference and the C++ forum to get a better idea how proper C++ is written. I don't want to post more here since this is after all, the C forum and nobody is required to understand C++.