Return s1 in the address of s2

[Lim Boon Jye]

#include <iostream>
#include<string>
using namespace std;

char * strstr(const char *, const char *);

void main()
{
	char input1[256] , input2[256];

	cout<<"Input 1 : ";
	cin.getline(input1,256);

	cout<<"Input 2 : ";
	cin.getline(input2,256);

	strstr(input1,input2);

	
}

char * strstr(
        const char * str1,
        const char * str2
        )
{
        char *cp = (char *) str1;
        char *s1, *s2;

        if ( !*str2 )
            return((char *)str1);

        while (*cp)
        {
                s1 = cp;
                s2 = (char *) str2;

                while ( *s1 && *s2 && !(*s1-*s2) )
                        s1++, s2++;

                if (!*s2)
                        return(cp);

                cp++;
        }

        return(NULL);


}

Can someone help me why i get error ? and help me to fix it?
trying many times already..

[Dash]

1) Use code tags.
2) What errors are you having ? Post them and we can help you.

[Lim Boon Jye]

1>c:\users\wendy chirs\desktop\inti\oop\jye\jye\jye\testingcall.cpp(5): error C2556: 'char *strstr(const char *,const char *)' : overloaded function differs only by return type from 'const char *strstr(const char *,const char *)'
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\string.h(196) : see declaration of 'strstr'
1>c:\users\wendy chirs\desktop\inti\oop\jye\jye\jye\testingcall.cpp(5): error C2373: 'strstr' : redefinition; different type modifiers
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\string.h(196) : see declaration of 'strstr'
1>c:\users\wendy chirs\desktop\inti\oop\jye\jye\jye\testingcall.cpp(26): error C2556: 'char *strstr(const char *,const char *)' : overloaded function differs only by return type from 'const char *strstr(const char *,const char *)'
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\string.h(196) : see declaration of 'strstr'
1>c:\users\wendy chirs\desktop\inti\oop\jye\jye\jye\testingcall.cpp(26): error C2491: 'strstr' : definition of dllimport function not allowed

[Dash]

Can you try changing you function's name ?

Edit: Don't use void main(). int main() is the right way to go.

[Lim Boon Jye]

Dash .
it's work after i changing the function name.
can i ask what problem to cause that?
Beside this .
i want to add-on a things that

Input 1 : class
Input 2 : roomclass

The class in the input 2 occur in the address of 4.


The 4 address how should i write it to show it?

Thanks by the way . u help me solve my toughest part

[Dash]

It's because there is a function named strstr that returns a const char*, and as the error says, you can't overload functions based on the return type alone.

[vlad from moscow]

There was no need to rename your function. You could access it by specifying global namespace as, for example:

::strstr(input1,input2);

[Lim Boon Jye]

vlad .
thanks .

okay. thanks anyways.
so the when i match the input .

then how should i print out the address ?

[R0mai]

vlad, I that doesn't solve the problem, as std::strstr() is defined in the std namespace AND in the global namespace as well: so ::strstr() would still clash with the standard strstr().

[Lim Boon Jye]

I don't know how to print out the address

Input 1 : Class
Input 2 : Theclass

The address of s1 in s2 is : 3

how to print out the 3?
i think my code should not be problem already?

[vlad from moscow]

@R0mai

vlad, I that doesn't solve the problem, as std::strstr() is defined in the std namespace AND in the global namespace as well: so ::strstr() would still clash with the standard strstr().

It is implementation defined whether C standard function are defined in the global namespace or not. Moreover in the original code the header <cstring> is not included. So it can be that in the header <string> only using declarations are used which do not include strstr.

[Lim Boon Jye]

i asking for so many times..

Any senior can help me please?

[R0mai]

You're right vlad. But in VS, (what OP is using) <cstring> is included (probably from <string>).

@Lim Boon Jye : You can do additive arithmetic with pointers, so subtract input1 from the result of strstr(). This should give you 3. (Of course, check for NULL before).

[Lim Boon Jye]

u Mean i add a

char *total;

total = input1 - 1;

i put this code inside my strstr() function isnt?

and put before return(null)?;

[Lim Boon Jye]

The result that i get from strstr() ;

where can i put my formula in? and check for NULL before is? sorry for that..

[R0mai]

I mean like this in your main :

char *result = strstr(input1, input2);
if ( !result ) {
    std::cout << result - input1 << std::endl;
} else {
    std::cout << "string not found" << std::endl;
}

Edit : edited if

[Lim Boon Jye]

after i put it.

It say the string not found .

#include <iostream>
#include<string>
using namespace std;

char * substr(const char *, const char *);

void main()
{
	char input1[256] , input2[256];
	char *back;
	cout<<"Input 1 : ";
	cin.getline(input1,256);

	cout<<"Input 2 : ";
	cin.getline(input2,256);

	char *result = substr(input1, input2);
	if ( result ) 
	{
		cout << "The string is at : "<<result - input1 << endl;
	}
	else
	{
		cout << "string not found" << endl;
	}
	cin.ignore();
}

char * substr(
        const char * str1,
        const char * str2
        )
{
        char *cp = (char *) str1;
        char *s1, *s2;

        if ( !*str2 )
            return((char *)str1);

        while (*cp)
        {
                s1 = cp;
                s2 = (char *) str2;

                while ( *s1 && *s2 && !(*s1-*s2) )
                        s1++, s2++;

                if (!*s2)
                        return(cp);

                cp++;
        }

        return(NULL);


}

[R0mai]

I'm sorry, you're right. The condition shoudl be if ( !result ).

[Lim Boon Jye]

this time my output is :

Input 1: yes
Input 2: ohyes

The string is at : -4650544

why de?

[Lim Boon Jye]

actually i wan my output is like dis :

Input 1: yes
Input 2: ohyes
The String s1 is start at s2 at : 2

Mean from [0] , [1] , then [2]