473,385 Members | 2,004 Online

# Function to determine the length of an integer string

Is there any function to determine the length of an integer string?

Dec 7 '05 #1
13 3611
strlen gives the length of string irrespective of its content (ie.
integer or character)

Dec 7 '05 #2

coinjo wrote:
Is there any function to determine the length of an integer string?

What is an integer string?

std::string has a function that returns its length.

If you have a variable of any of the integer types, you can turn the
number it represents into a string using a stringstream (you can even
choose decimal, hexadecimal or octal representation by using the
appropriate stream manipulators). Once you've done that, you can ask
the string how long it is.

If none of that helps, post some code to show what you are trying to
do.

Gavin Deane

Dec 7 '05 #3

coinjo wrote:
Is there any function to determine the length of an integer string?

Take the logrithm of the value (rounded down to an integer) then add
one.

Note that the base of the logrithm has to match the base used to
represent the value. For example, if the number is 100 decimal, the
equation would be:

Log10(100)+1 = 3

so 100 has 3 digits as a decimal number.

Greg

Dec 7 '05 #4
#include<iostream>
#include<fstream>
using namespace std;

void selectionSort(int list[], int length)
{
int index;
int smallestIndex;
int minIndex;
int temp;

for(index=0; index<length-1; index++)
{
smallestIndex=index;

for(minIndex=index+1; minIndex<length; minIndex++)
if(list[minIndex]<list[smallestIndex])
smallestIndex=minIndex;
temp=list[smallestIndex];
list[smallestIndex]=list[index];
list[index]=temp;
}
};

int main()
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");

selectionSort(s,10);

while(a>>s[count] && !a.eof())
{
count++;
}

c=strlen(s);
return 0;
}

in.txt contains:
9
8
7
6
5
4
3
2
1

whether i include cstring file or not i get an error message in vc++;
(40) : error C2664: 'strlen' : cannot convert parameter 1 from 'int
[100]' to 'const char *'
Types pointed to are unrelated; conversion requires
reinterpret_cast, C-style cast or function-style cast

Dec 7 '05 #5

coinjo wrote:
#include<iostream>
#include<fstream>
using namespace std;

void selectionSort(int list[], int length)
{
<snip contents of this function that operates on values in the list
array>
};
Spurious semicolon. It can go.
int main()
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");

selectionSort(s,10);
There is nothing in s at the moment. What do you think selectionSort is
going to do? If it touches any of the uninitialised int varaibles in s
(which it does) then you have undefined behaviour. Which is bad.
while(a>>s[count] && !a.eof())
{
count++;
}

c=strlen(s);

If we ignore the problem call to selectionSort, it looks like you have
an int array s with the first count elements holding the values read
from in.txt. And if I've understood, you want to know the total number
of digits in all those ints.

Using the technique posted by Greg, change you while loop to

int total_digits = 0;
while(a>>s[count] && !a.eof())
{
total_digits += log10(s[count]) + 1;
count++;
}

You'll need to #include<math.h> to get the log10 function. And note
that this will count decimal digits.

Gavin Deane

Dec 7 '05 #6
coinjo wrote:

whether i include cstring file or not i get an error message in vc++;
(40) : error C2664: 'strlen' : cannot convert parameter 1 from 'int
[100]' to 'const char *'
Types pointed to are unrelated; conversion requires
reinterpret_cast, C-style cast or function-style cast

The strlen() function works by searching the string for the special
text character '\0'. As 0 is a valid integer, and in no way special,
int arrays are not terminated in that way.

If size in important, either keep track of it or scrap arrays and use
vectors. At your level of skill, vectors are the better choice by far.

Brian
Dec 7 '05 #7
coinjo wrote:
#include<iostream>
#include<fstream>
using namespace std;
http://www.parashift.com/c++-faq-lit....html#faq-27.5
void selectionSort(int list[], int length)
{
int index;
int smallestIndex;
int minIndex;
int temp;
http://www.parashift.com/c++-faq-lit....html#faq-27.7
for(index=0; index<length-1; index++)
http://www.parashift.com/c++-faq-lit...html#faq-13.15
{
smallestIndex=index;

for(minIndex=index+1; minIndex<length; minIndex++)
if(list[minIndex]<list[smallestIndex])
smallestIndex=minIndex;

temp=list[smallestIndex];
list[smallestIndex]=list[index];
list[index]=temp;
std::swap(list[smallestIndex], list[index]);
}
};

int main()
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");
ifstream in("in.txt");

Use constructors and descriptive names.
selectionSort(s,10);
Don't you want to sort *after* reading?
while(a>>s[count] && !a.eof())
This will fail if the file contains something else than integers.
{
count++;
}
You could also do

while (in >> s[count++])
;

std::sort(s, s+count);
c=strlen(s);
See below.
return 0;
}

in.txt contains:
9
8
7
6
5
4
3
2
1

whether i include cstring file or not i get an error message in vc++;
(40) : error C2664: 'strlen' : cannot convert parameter 1 from 'int
[100]' to 'const char *'
Types pointed to are unrelated; conversion requires
reinterpret_cast, C-style cast or function-style cast

An "integer string" does not exist, it makes no sense. A string is a
sequence of characters, so that would be an "integer sequence of
characters". strlen() works with a sequence of char's, nothing else.
wcslen() works with a sequence of wchar_t's.

However, a sequence of ints may be a string (for example, an
implementation could have a character set, such as unicode, which would
be encoded on 32-bit unsigned ints), but in this case we would not call
this an "integer string" (because that's not what it is), but a "wide
character string" or something like that.

Semantically, you are not working on a "string", but on a container of
ints. Although both could be implemented the same way
(container-of-chars, container-of-ints), they are different.
IIUC, you want to determine the number of integers that were read from
the file (the "length" of your "string", or more specifically, the
number of elements in your container). You have several ways to do
that:

2) use a container

std::vector<int> v;

int temp=0;
while (in >> temp)
v.push_back(temp);

int count = v.length();

3) use an "end" value, such as 0

int s[100] = {0};

int count=0;
for (int i=0; s[i] != 0; ++i)
++count;

But that will work only if 0 is not a valid value.

4) Embed the number of elements in the file (as the first line for
example)
Jonathan

Dec 7 '05 #8
#include<iostream.h>
#include<fstream>
#include<cstring>
#include<math.h>
using namespace std;

void selectionSort(int list[], int length)
{
int index;
int smallestIndex;
int minIndex;
int temp;

for(index=0; index<length-1; index++)
{
smallestIndex=index;

for(minIndex=index+1; minIndex<length; minIndex++)
if(list[minIndex]<list[smallestIndex])
smallestIndex=minIndex;
temp=list[smallestIndex];
list[smallestIndex]=list[index];
list[index]=temp;
}
};

void main()
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");

int total_digits = 0;

while(a>>s[count] && !a.eof())
{
total_digits += log10(s[count]) + 1;
count++;
}

count=0;
selectionSort(s,total_digits);

while(count<total_digits)
{
cout<<s[count]<<endl;
count++;
}
}
Thanks to all of you for your generous help, I now have come up with
this and as far as i thinks, it works! Please post any suggestions or
corrections (if there are any) to this.

Dec 8 '05 #9
#include<iostream.h>
#include<fstream>
#include<cstring>
#include<math.h>
using namespace std;

void selectionSort(int list[], int length)
{
int index;
int smallestIndex;
int minIndex;
int temp;

for(index=0; index<length-1; index++)
{
smallestIndex=index;

for(minIndex=index+1; minIndex<length; minIndex++)
if(list[minIndex]<list[smallestIndex])
smallestIndex=minIndex;
temp=list[smallestIndex];
list[smallestIndex]=list[index];
list[index]=temp;
}
};

void main()
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");

int total_digits = 0;

while(a>>s[count] && !a.eof())
{
total_digits += log10(s[count]) + 1;
count++;
}

count=0;
selectionSort(s,total_digits);

while(count<total_digits)
{
cout<<s[count]<<endl;
count++;
}
}
Thanks to all of you for your generous help, I now have come up with
this and as far as i thinks, it works! Please post any suggestions or
corrections (if there are any) to this.

Dec 8 '05 #10
#include<iostream.h>
#include<fstream>
#include<cstring>
#include<math.h>
using namespace std;

void selectionSort(int list[], int length)
{
int index;
int smallestIndex;
int minIndex;
int temp;

for(index=0; index<length-1; index++)
{
smallestIndex=index;

for(minIndex=index+1; minIndex<length; minIndex++)
if(list[minIndex]<list[smallestIndex])
smallestIndex=minIndex;
temp=list[smallestIndex];
list[smallestIndex]=list[index];
list[index]=temp;
}
};

void main()
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");

int total_digits = 0;

while(a>>s[count] && !a.eof())
{
total_digits += log10(s[count]) + 1;
count++;
}

count=0;
selectionSort(s,total_digits);

while(count<total_digits)
{
cout<<s[count]<<endl;
count++;
}
}
Thanks to all of you for your generous help, I now have come up with
this and as far as i thinks, it works! Please post any suggestions or
corrections (if there are any) to this.

Dec 8 '05 #11
coinjo wrote:

A single post would have done the job, you know.
#include<iostream.h>
Non standard.

# include <iostream>

Seriously, this won't compile with a modern compiler. Visual C++ 8
rejects this.
#include<fstream>
#include<cstring>
#include<math.h>
Prefer <cmath>
using namespace std;

void selectionSort(int list[], int length)
{
int index;
int smallestIndex;
int minIndex;
int temp;
This is *not* a good way to program in C++. You have been given some
is "better".
for(index=0; index<length-1; index++)
{
smallestIndex=index;

for(minIndex=index+1; minIndex<length; minIndex++)
if(list[minIndex]<list[smallestIndex])
smallestIndex=minIndex;
temp=list[smallestIndex];
list[smallestIndex]=list[index];
list[index]=temp;
}
};

void main()
Illegal, main() returns an int.
{
int s[100];
int c=0;
int count=0;
ifstream a;
a.open("in.txt");

int total_digits = 0;

while(a>>s[count] && !a.eof())
{
total_digits += log10(s[count]) + 1;
count++;
}

count=0;
selectionSort(s,total_digits);
This won't work. For example, if each number has two digits and you
have 60 numbers, you'll read past the array. This should be

selectionSort(s, count);

but don't reset count to 0 before.
while(count<total_digits)
{
cout<<s[count]<<endl;
Again, this is undefined behavior if total_digits is >= 100.
count++;
}
}
Thanks to all of you for your generous help, I now have come up with
this and as far as i thinks, it works! Please post any suggestions or
corrections (if there are any) to this.

Jonathan

Dec 8 '05 #12

Jonathan Mcdougall wrote:
coinjo wrote:
#include<math.h>

Prefer <cmath>

The jury's out on that one. My preference is for <xxx.h> rather than
<cxxx>. See P J Plauger's posts in this thread

Gavin Deane

Dec 8 '05 #13
coinjo wrote:

Thanks to all of you for your generous help, I now have come up with
this and as far as i thinks, it works! Please post any suggestions or
corrections (if there are any) to this.

Why did you ignore most of the advice given to you?
Brian

--
Please quote enough of the previous message for context. To do so from
Google, click "show options" and use the Reply shown in the expanded
Dec 8 '05 #14

This thread has been closed and replies have been disabled. Please start a new discussion.

### Similar topics

 9 by: Penn Markham | last post by: Hello all, I am writing a script where I need to use the system() function to call htpasswd. I can do this just fine on the command line...works great (see attached file, test.php). When my... 10 by: Mamuninfo | last post by: Hello, Have any function in the DB2 database that can generate unique id for each string like oracle, mysql,sybase,sqlserver database. In mysql:- select md5(concat_ws("Row name")) from... 2 by: pangel83 | last post by: I've been trying for days to write a piece of VB.NET code that will read from winamp's memory space the paths of the files from the current winamp playlist. The GETPLAYLISTFILE command of the... 19 by: Gary Kahrau | last post by: I want to create a function and can only get half way to my goal. dim sStr as string sStr = Entry(2,"a,b,c,d") ' Sets sStr = "b" Entry(2,sStr) = "B" ' Sets sStr = "a,B,c,d"... 11 by: youngster94 | last post by: Hey all, I've written a VB.Net app that creates picture badges complete with barcodes. The problem is that the barcode quality is not good enough to be read by scanners. I'm using the... 10 by: Robert Skidmore | last post by: Take a look at this new JS function I made. It is really simple but very powerful. You can animate any stylesheet numeric value (top left width height have been tested), and works for both % and px... 6 by: daveyand | last post by: Hey Guys, I've stumped. I created a function that does various things to select boxes. Namely Get All selected indexes, populate array with these values 3 by: =?Utf-8?B?SmFuIEhlcHBlbg==?= | last post by: Hi, I've a question. I'm developing a windows application and for the application i need to run functions and procedures that are stored in a database. Here is an example that i tried to get... 14 by: nishit.gupta | last post by: Is their any single fuction available in C++ that can determine that a string contains a numeric value. The value cabn be in hex, int, float. i.e. "1256" , "123.566" , "0xffff" , It can also... 0 by: taylorcarr | last post by: A Canon printer is a smart device known for being advanced, efficient, and reliable. It is designed for home, office, and hybrid workspace use and can also be used for a variety of purposes. However,... 0 by: Charles Arthur | last post by: How do i turn on java script on a villaon, callus and itel keypad mobile phone 0 by: ryjfgjl | last post by: In our work, we often receive Excel tables with data in the same format. If we want to analyze these data, it can be difficult to analyze them because the data is spread across multiple Excel files... 0 by: emmanuelkatto | last post by: Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud. Please let me know. Thanks! Emmanuel 1 by: nemocccc | last post by: hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions? 1 by: Sonnysonu | last post by: This is the data of csv file 1 2 3 1 2 3 1 2 3 1 2 3 2 3 2 3 3 the lengths should be different i have to store the data by column-wise with in the specific length. suppose the i have to... 0 by: Hystou | last post by: There are some requirements for setting up RAID: 1. The motherboard and BIOS support RAID configuration. 2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2... 0 by: marktang | last post by: ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However,... 0 by: Oralloy | last post by: Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers,...