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Simple question with array of strings

P: n/a
Hi,

This may look as a smiple task to most of you, but to me (a beginner
with C), it drives me crazy.

All I want is that one function passes a two dimensional array of
strings to another function.

example:
NOTE: the strings can be of different length and the array will be
initialized many times to differnt values.

void fun_1()
{
char **Arr[3][2]= {'\0'}; //I want to define a 3x2 array of strings
of
//different length (max 32 ch)
//Arr initialization
// Arr ["ONE", "1"]
// ["Two", "2"]
// ["THREE", "3"]

fun2(Arr);
}

void fun_2(char **rcvArr)
{

}

CAn anybody help me with how to define it, how to initialize it and
hwo to send and receive it as a parameter.

I suspect that I must define some buffer length. The question is
should I select fixed length (e.g. 32 ch per string) or a veriable
length. In the other option I would probably need to use malloc in
order to allocate memory...

I would be happy to be advised of the best way to do it. Also, when I
initialize the array, I preffer that it will take as little text space
as possible (for example, the best will be to define it all in one
line!).

Thanks for helping
Rafi
Jul 22 '05 #1
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9 Replies


P: n/a
ra*******@telrad.co.il (Rafi Kfir) writes:
Hi, This may look as a smiple task to most of you, but to me (a beginner
with C), it drives me crazy. All I want is that one function passes a two dimensional array of
strings to another function.
... I would be happy to be advised of the best way to do it.

Look up <vector> and <string> in a C++ book - or online.
Jul 22 '05 #2

P: n/a
Rafi Kfir wrote:
This may look as a smiple task to most of you, but to me (a beginner
with C), it drives me crazy.
If you need help with C, you should consider comp.lang.c as your NG of
choice.
All I want is that one function passes a two dimensional array of
strings to another function.

example:
NOTE: the strings can be of different length and the array will be
initialized many times to differnt values.

void fun_1()
{
char **Arr[3][2]= {'\0'}; //I want to define a 3x2 array of strings
of
//different length (max 32 ch)
In C++ one should always consider standard containers for that:

vector<vector<string> > Arr;

In C you probably will want to declare an array of pointers to char:

char *Arr[3][2] = { 0 };

and then somehow allocate the memory. Although, I'd susupect that to
have an array of 33-char arrays would be easier (since you limited your
strings to 32 bytes):

char Arr[3][2][33];
//Arr initialization
// Arr ["ONE", "1"]
// ["Two", "2"]
// ["THREE", "3"]
If you declare your array as 3-dimensional, you still should be able to
initialise it as

char Arr[3][2][33] =
{ { "ONE", "1" }, { "Two", "2" }, { "Three", "3" } };

fun2(Arr);
}

void fun_2(char **rcvArr)
Just repeat the declaration of the Arr in your function declaration (but
pick the right name for it first, 'fun2' or 'fun_2'):

void funX(char Arr[3][2][33])
{

}

CAn anybody help me with how to define it, how to initialize it and
hwo to send and receive it as a parameter.
How about a book on C? Do you have any?
I suspect that I must define some buffer length. The question is
should I select fixed length (e.g. 32 ch per string) or a veriable
length. In the other option I would probably need to use malloc in
order to allocate memory...
Right.
I would be happy to be advised of the best way to do it.
There is no "best" way to skin the proverbial cat. There is always more
than one way and each has its advantages and drawbacks.
Also, when I
initialize the array, I preffer that it will take as little text space
as possible (for example, the best will be to define it all in one
line!).


Yes, you could do that too if your array doesn't change. But it's usually
a maintenance nightmare.

const char arr_[] = "ONE\01\0Two\02\0THREE\03\0";
/* ^0 ^4 ^6 ^10^12 ^18
const char* const Arr[3][2] =
{{ arr_, arr_+ 4 }, { arr_+ 6, arr_+ 10 }, { arr_+12, arr_+18 }};

V
Jul 22 '05 #3

P: n/a

"Rafi Kfir" <ra*******@telrad.co.il> wrote in message
news:f7**************************@posting.google.c om...
Hi,

This may look as a smiple task to most of you, but to me (a beginner
with C), it drives me crazy.
news:comp.lang.c if you really are interested in C and not C++.

All I want is that one function passes a two dimensional array of
strings to another function.
It's impossible to pass arrays in C or C++. You have to use pointers
instead. This is one reason (among many) to use vectors instead of arrays in
C++.

example:
NOTE: the strings can be of different length and the array will be
initialized many times to differnt values.

void fun_1()
{
char **Arr[3][2]= {'\0'}; //I want to define a 3x2 array of strings
char* Arr[3][2] = { { "ONE", "1" }, { "TWO", "2" }, { "THREE", "3" } };
of
//different length (max 32 ch)
//Arr initialization
// Arr ["ONE", "1"]
// ["Two", "2"]
// ["THREE", "3"]

fun2(Arr);
}

void fun_2(char **rcvArr)
void fun_2(char* (*rcvArr)[2])

Horrible.
{

}

CAn anybody help me with how to define it, how to initialize it and
hwo to send and receive it as a parameter.

I suspect that I must define some buffer length. The question is
should I select fixed length (e.g. 32 ch per string) or a veriable
length. In the other option I would probably need to use malloc in
order to allocate memory...
Yes, you are right.

I would be happy to be advised of the best way to do it. Also, when I
initialize the array, I preffer that it will take as little text space
as possible (for example, the best will be to define it all in one
line!).


Decide what you are programming, C or C++. Post to the appropriate
newsgroup.

If you are programming C then you have to do something like the rubbish
above.

If you are programming C++, then you can use vector and string and forget
about the rubbish above.

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

struct StringPair
{
StringPair(string f, string s)
{
first = f;
second = s;
}
string first;
string second;
};

typedef vector<StringPair> StringArray;

void fun_2(StringArray& Arr)
{
// do something with Arr
}

int main()
{
StringArray Arr;
Arr.push_back(StringPair("ONE", "1"));
Arr.push_back(StringPair("TWO", "2"));
Arr.push_back(StringPair("THREE", "3"));
}

Now don't you think that a bit easier. Everything is dynamic, everything
gets freed automatically.

john
Jul 22 '05 #4

P: n/a
#include <stdlib.h>
#include <stdio.h>

void print(char *arg[])
{
int i,j;
for( i = 0; i < 3; i++)
{
for( j = 0; j < 4; j++)
{
printf("%c",arg[i][j]);
}
printf("\n");
}
}

int main()
{
char **ch;
int i,j;

ch = (char**)calloc(3,sizeof(char*));
for(i = 0; i < 3; i++)
{
ch[i] = (char *)calloc(4,sizeof(char));
}
for(i = 0; i < 3; i++)
{
for(j = 0; j < 4; j++)
{
ch[i][j] = 'c';
}
}
print(ch);

return 0;
}

Jul 22 '05 #5

P: n/a
#include <stdlib.h>
#include <stdio.h>

void print(char *arg[])
{
int i,j;
for( i = 0; i < 3; i++)
{
for( j = 0; j < 4; j++)
{
printf("%c",arg[i][j]);
}
printf("\n");
}
}

int main()
{
char **ch;
int i,j;

ch = (char**)calloc(3,sizeof(char*));
for(i = 0; i < 3; i++)
{
ch[i] = (char *)calloc(4,sizeof(char));
}
for(i = 0; i < 3; i++)
{
for(j = 0; j < 4; j++)
{
ch[i][j] = 'c';
}
}
print(ch);

return 0;
}

Jul 22 '05 #6

P: n/a
#include <stdlib.h>
#include <stdio.h>

void print(char *arg[])
{
int i,j;
for( i = 0; i < 3; i++)
{
for( j = 0; j < 4; j++)
{
printf("%c",arg[i][j]);
}
printf("\n");
}
}

int main()
{
char **ch;
int i,j;

ch = (char**)calloc(3,sizeof(char*));
for(i = 0; i < 3; i++)
{
ch[i] = (char *)calloc(4,sizeof(char));
}
for(i = 0; i < 3; i++)
{
for(j = 0; j < 4; j++)
{
ch[i][j] = 'c';
}
}
print(ch);

return 0;
}

Jul 22 '05 #7

P: n/a
oops, guess i should have read the bright red instruction at the top of the
page telling me not to resubmit if my reply doent show up right away. sorry
about that

Jul 22 '05 #8

P: n/a
In article <f7**************************@posting.google.com >,
Rafi Kfir <ra*******@telrad.co.il> wrote:

This may look as a smiple task to most of you, but to me (a beginner
with C), it drives me crazy.

All I want is that one function passes a two dimensional array of
strings to another function.
Doing this using old-style arrays and char* "strings" is *not* a simple
task, even for experienced programmers. C++ has tools that make it much
easier, namely the standard 'vector' and 'string' data types.
example:
NOTE: the strings can be of different length and the array will be
initialized many times to differnt values.
No problem. The standard 'string' type automatically resizes itself
appropriately.

#include <vector>
#include <string>

using namespace std;
void fun_1()
{
char **Arr[3][2]= {'\0'}; //I want to define a 3x2 array of strings
of
//different length (max 32 ch)
//Arr initialization
// Arr ["ONE", "1"]
// ["Two", "2"]
// ["THREE", "3"]
vector<vector<string> > Arr (3, vector<string>(2));
Arr[0][0] = "ONE";
Arr[0][1] = "1";
// etc. for the other elements

fun2(Arr);
}

void fun_2(char **rcvArr)
void fun_2 (vector<vector<string> >& rcvArr)
// and make it const if you don't plan to modify the data inside the
// function{

}


--
Jon Bell <jt*******@presby.edu> Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA
Jul 22 '05 #9

P: n/a

void Func(char**);
//I don't work with pointers to pointers much
//so I'd have to look-up the correct way to make
//the above argument const-correct.

int main()
{
char* string_array[3][2];

string_array[0][0] = "One";
string_array[0][1] = "1";
string_array[1][0] = "Two";
string_array[1][1] = "2";
string_array[2][0] = "Three";
string_array[2][1] = "3";

Func(string_array);
}

void Func(char** string_array);
{

}
-JKop
Jul 22 '05 #10

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