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VB's Left, Right, Mid Functions in C++?

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VB's Left, Right, Mid Functions in C++?

Sep 15th, 2003

I apologize up front; I'm a VB Programmer trying to pick up C++. I have a very simple program that takes a string input from the user. How can I look at a specific character in that string? VB has the Left(), Right(), and Mid() Functions. Is there something similar for C++? A sample of my code is below. In this example, how could I have the program return the "T" in "Test String" or the "g" at the end?

#include "stdafx.h"
#include <iostream>
#include <string>

#using <mscorlib.dll>

using namespace System;
using namespace std;

int _tmain()
{
string strTest;
strTest = "Test String";
cout << strTest;

return 0;
}

Joe Cody
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Re: VB's Left, Right, Mid Functions in C++?

Sep 15th, 2003

Left could be done by going:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 
char left(char *string) {
return string[0];
}
char left(char *string) {
return string[0];
}

Right could be done like this:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char right(char *string) {
return string[strlen(string)];
}
char right(char *string) {
return string[strlen(string)];
}

I'm no VB programmer, since it's my personal opinion that VB is for idiots, so I don't know what mid() does. If it gets the middle character:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char mid(char *string) {
return string[strlen(string)>>1);
}
char mid(char *string) {
return string[strlen(string)>>1);
}

Does this help?

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Re: Re: VB's Left, Right, Mid Functions in C++?

Sep 16th, 2003

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Originally Posted by Mike29936

I'm no VB programmer, since it's my personal opinion that VB is for idiots, so I don't know what mid() does.

Well this isn't very nice, is it? (although.. i prefer C/C++ myself)

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Daywalker46410 Daywalker46410 is offline

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Sep 16th, 2003

I'm assuming I create these as functions, but I get an error when calling them.

error C2665: 'std::right' : none of the 2 overloads can convert parameter 1 from type 'std::string'

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Re: VB's Left, Right, Mid Functions in C++?

Sep 16th, 2003

Did you declear the functions? May be there are these functions in reality since std::right would seem as if it thinks it is one of the library functions.. rename them to something like rightc() or smthn..
IIya

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Originally Posted by Daywalker46410

I'm assuming I create these as functions, but I get an error when calling them.

error C2665: 'std::right' : none of the 2 overloads can convert parameter 1 from type 'std::string'

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Re: VB's Left, Right, Mid Functions in C++?

Sep 16th, 2003

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none of the 2 overloads can convert parameter 1 from type 'std::string'

It does strings, as in the character arrays. It doesn't do objects.

To get it to work, you have to do something like this:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char *string = "Hello. I am a string";
cout << right(string);
char *string = "Hello. I am a string";
cout << right(string);

If there actually is a 'right()' function in there somewhere, I believe this will work:

::right(string);

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Re: Re: VB's Left, Right, Mid Functions in C++?

Sep 16th, 2003

I think he was using strings all along..

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Originally Posted by Mike29936

It does strings, as in the character arrays. It doesn't do objects.

To get it to work, you have to do something like this:
Help with Code Tags

C++ Syntax (Toggle Plain Text)
char *string = "Hello. I am a string";
cout << right(string);
char *string = "Hello. I am a string"; cout << right(string);
If there actually is a 'right()' function in there somewhere, I believe this will work:

::right(string);

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Re: VB's Left, Right, Mid Functions in C++?

Dec 1st, 2003

u lot talking about left and right ok BUT i can't get my head around this,

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
1    For x = 1 to Len(txtNI.Text)   
2    If Asc(Mid(txtNi,x,1) < 65 or _
3    Asc(Mid(txtNi,x,1) > 90 Then
.....
1    For x = 1 to Len(txtNI.Text)   
2    If Asc(Mid(txtNi,x,1) < 65 or _
3    Asc(Mid(txtNi,x,1) > 90 Then
.....

I know this, on the first line of the code, Len function is looping and looking at each character in a string that has been entered in txtNi. Then on the second line Asc checks for Ascii characters all fine till here, i don't understand this part..

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
...
(Mid(txtNi,x,1) < 65
...
...
(Mid(txtNi,x,1) < 65
...

can anyway explain this plz?

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Re: VB's Left, Right, Mid Functions in C++?

Dec 4th, 2003

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <stdlib.h>
#include <string>
 
#define ONE " via c++ string at() (worx only on 1 char): "
#define MORE " via c++ string substr() (worx on more chars): "
 
using namespace std;
 
int main(void)
{
    string test;
 
    do 
    {
        cout << "Enter the teststring (6 chars minimum): ";
        cin >> test;
    }
    while (test.size() < 6);
 
    /* u could actually use more chars with substr() method than just one
     * for example u could replace the test.substr(0, 1) with test.substr(0, 2)
     * to get 2 chars
     */
    cout << "\n\tleft()" << MORE << test.substr(0, 1) << "\n";
    cout << "\tleft()" << ONE << test.at(0) << "\n\n";
 
    cout << "\tright()" << MORE << test.substr(test.size() - 1, 1) << "\n";
    cout << "\tright()" << ONE << test.at(test.size() - 1) << "\n\n";
 
    /* here i extracted the 5th char, remember counting in c / c++ begins at 0, not at 1 */
    cout << "\tmid()" << MORE << test.substr(4, 1) << "\n";
    cout << "\tmid()" << ONE  << test.at(4) << "\n\n";
 
    system("PAUSE");	
    return 0;
}
#include <iostream>
#include <stdlib.h>
#include <string>

#define ONE " via c++ string at() (worx only on 1 char): "
#define MORE " via c++ string substr() (worx on more chars): "

using namespace std;

int main(void)
{
    string test;
    
    do 
    {
        cout << "Enter the teststring (6 chars minimum): ";
        cin >> test;
    }
    while (test.size() < 6);
    
    /* u could actually use more chars with substr() method than just one
     * for example u could replace the test.substr(0, 1) with test.substr(0, 2)
     * to get 2 chars
     */
    cout << "\n\tleft()" << MORE << test.substr(0, 1) << "\n";
    cout << "\tleft()" << ONE << test.at(0) << "\n\n";
    
    cout << "\tright()" << MORE << test.substr(test.size() - 1, 1) << "\n";
    cout << "\tright()" << ONE << test.at(test.size() - 1) << "\n\n";
    
    /* here i extracted the 5th char, remember counting in c / c++ begins at 0, not at 1 */
    cout << "\tmid()" << MORE << test.substr(4, 1) << "\n";
    cout << "\tmid()" << ONE  << test.at(4) << "\n\n";
    
    system("PAUSE");	
    return 0;
}

this is actually some source who should illustrate you the use of the c++ string class (which is very handy) in order to simulate the vb functions u asked for, so u dont need your own functions for it, since all is already in c++ :cheesy: