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Alphabet to Integer conversion program== Segmentation Fault.

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Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

I am getting a segmentation fault when i run the follwing program.
This program takes in a const char* and returns the integer format.

I also need advice on converting a C++ Octal or Hexadecimal Notationed string to an integer.

Here is the code

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <cstring>
 
int atoi(const char*);
int single_char_convert(char);
int pow(int,int); 
int main()
{
std::cout<<atoi("123");
}
 
int atoi(const char *str)
{
	int length=std::strlen(str)-1;
	int result=0;
	for(int x=0;x<=length;x++)
	{
		int y=length-x;
		char character=str[x];
		int converted_char=single_char_convert(character);
		result+=(converted_char*pow(10,y));			
	}
	return result;
}
 
int single_char_convert(char a)
{
	switch(a)
	{
		case '0':
			return 0;
		case '1':
			return 1;
		case '2':
			return 2;
		case '3':
			return 3;
		case '4':
			return 4;
		case '5':
			return 5;
		case '6':
			return 6;
		case '7':
			return 7;
		case '8':
			return 8;
		case '9':
			return 9;
	}
}
 
int pow(int number,int powerof)
{
	if(powerof==1)
	{
	return number;
	}
	else
	{
	return number*pow(number,--powerof);
	}
}
#include <iostream>
#include <cstring>

int atoi(const char*);
int single_char_convert(char);
int pow(int,int); 
int main()
{
std::cout<<atoi("123");
}

int atoi(const char *str)
{
	int length=std::strlen(str)-1;
	int result=0;
	for(int x=0;x<=length;x++)
	{
		int y=length-x;
		char character=str[x];
		int converted_char=single_char_convert(character);
		result+=(converted_char*pow(10,y));			
	}
	return result;
}

int single_char_convert(char a)
{
	switch(a)
	{
		case '0':
			return 0;
		case '1':
			return 1;
		case '2':
			return 2;
		case '3':
			return 3;
		case '4':
			return 4;
		case '5':
			return 5;
		case '6':
			return 6;
		case '7':
			return 7;
		case '8':
			return 8;
		case '9':
			return 9;
	}
}

int pow(int number,int powerof)
{
	if(powerof==1)
	{
	return number;
	}
	else
	{
	return number*pow(number,--powerof);
	}
}

Code tags work sometimes and code tags donot work.

Last edited by Sky Diploma; May 1st, 2009 at 1:13 pm. Reason: Code tag isnt taking a copy paste maybe

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

>I also need advice on converting a C++ Octal or Hexadecimal Notationed string to an integer.

To do conversions between numbers and strings stringstreams are often used

Lines 28-50 can be replaced by: return a-'0';

Last edited by tux4life; May 1st, 2009 at 1:26 pm.

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

>I am getting a segmentation fault when i run the follwing program.
How does your code handle N^0?

>Code tags work sometimes and code tags donot work.
Define "do not work".

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

•

Originally Posted by tux4life

>I also need advice on converting a C++ Octal or Hexadecimal Notationed string to an integer.

To do conversions stringstreams are often used

Well True,
I pretty much dont know whether I can use stringstreams to solve this exercise.

•

Originally Posted by The C++ Programming Language Edition 3 by Bjarne Stroustrup has this Assignment in 6.6.16

Write a function atoi(const char*) that takes a string containing digits and returns the corresponding ints. for example
atoi("123")
returns 123

Modify atoi () to handle C++ octal and hexadecimal notations in addition to decimal numbers and also character constant notations

Will a-'0';
be true for all the constants.in different character map sets?

Narue thanks for the reply

Here is the new code

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <cstring>
 
int atoi(const char*);
int single_char_convert(char);
int pow(int,int); 
int main()
{
std::cout<<atoi("123");
}
 
int atoi(const char *str)
{
	int length=std::strlen(str)-1;
	int result=0;
	for(int x=0;x<=length;x++)
	{
		int y=length-x;
		char character=str[x];
		int converted_char=single_char_convert(character);
		result+=(converted_char*pow(10,y));			
	}
	return result;
}
 
int single_char_convert(char a)
{
	switch(a)
	{
		case '0':
			return 0;
		case '1':
			return 1;
		case '2':
			return 2;
		case '3':
			return 3;
		case '4':
			return 4;
		case '5':
			return 5;
		case '6':
			return 6;
		case '7':
			return 7;
		case '8':
			return 8;
		case '9':
			return 9;
	}
}
 
int pow(int number,int powerof)
{
	if (powerof==0)
	{
	return 1;
	}
	else
	{
	return number*pow(number,--powerof);
	}
}
#include <iostream>
#include <cstring>

int atoi(const char*);
int single_char_convert(char);
int pow(int,int); 
int main()
{
std::cout<<atoi("123");
}

int atoi(const char *str)
{
	int length=std::strlen(str)-1;
	int result=0;
	for(int x=0;x<=length;x++)
	{
		int y=length-x;
		char character=str[x];
		int converted_char=single_char_convert(character);
		result+=(converted_char*pow(10,y));			
	}
	return result;
}

int single_char_convert(char a)
{
	switch(a)
	{
		case '0':
			return 0;
		case '1':
			return 1;
		case '2':
			return 2;
		case '3':
			return 3;
		case '4':
			return 4;
		case '5':
			return 5;
		case '6':
			return 6;
		case '7':
			return 7;
		case '8':
			return 8;
		case '9':
			return 9;
	}
}

int pow(int number,int powerof)
{
	if (powerof==0)
	{
	return 1;
	}
	else
	{
	return number*pow(number,--powerof);
	}
}

Last edited by Sky Diploma; May 1st, 2009 at 1:42 pm.

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

•

Originally Posted by Sky Diploma

Well True,
I pretty much dont know whether I can use stringstreams to solve this exercise.

You can: if you convert the C++ string back to a C-string after the conversion, but that was probably not the intention of the assignment

Last edited by tux4life; May 1st, 2009 at 1:43 pm.

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

>Will a-'0';
>be true for all the constants.in different character map sets?
Digits are required by the C++ standard to be contiguous, but if you need to convert to hexadecimal, you can't portably use that trick. Try an array instead, using the index as your value:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
const char digits[] = "0123456789ABCDEF";
const char digits[] = "0123456789ABCDEF";

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

Narue, you're right but I provided him with this trick because his function was returning an integer value ...

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

Hey can you explain me of converting a string of char containing a hex notation of a number to a int?

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Re: Alphabet to Integer conversion program== Segmentation Fault.

May 1st, 2009

•

Originally Posted by Sky Diploma

Hey can you explain me of converting a string of char containing a hex notation of a number to a int?

Take a look at this

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Re: Alphabet to Integer conversion program== Segmentation Fault.

#10

May 1st, 2009

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Originally Posted by tux4life

Narue, you're right but I provided him with this trick because his function was returning an integer value ...

And that makes a difference, how?

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