Declaration problem on C

Question

3.00/5 (3 votes)

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C#

#include<stdio.h>
#define MONTHS 13
int main(void)
{
    char m[MONTHS] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
    int i;
    print("%s%13s", "Input", "output");
    for(i=1 ; i<MONTHS ; i++){
        printf("%7c%13c", i, m);
    }
    return 0;
}

This is my coding and may i know is it the declaration of the variable char wrong?

Posted 26-Apr-11 9:34am

Jayfam

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3 solutions

Solution 3

It is wrong because you declare an array of characters and try to initialize it with an array of (const) character pointers. The right code would be:

const char * m[] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

(you don't really need to define MONTHS).

Posted 26-Apr-11 10:09am

CPallini

Comments

Albert Holguin 26-Apr-11 16:13pm

my 5

CPallini 26-Apr-11 16:37pm

Thank you.

Jayfam 26-Apr-11 16:16pm

thanks

CPallini 26-Apr-11 16:37pm

You are welcome.

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Nish Nishant · Accepted Answer · 2011-04-26T09:40:00

Solution 1

Try something like this:

C++

#define MONTHS 12

char* m[MONTHS] =
{
"January", "February", "March",
"April", "May", "June",
"July", "August", "September",
"October", "November", "December"
};

int i;

for(i=0 ; i<MONTHS ; i++)
{
    printf("%d: %s\n", i + 1, *(m + i));
}

Note how I've created an array of char* (and not an array of char).

Posted 26-Apr-11 9:40am

Nish Nishant

Comments

Jayfam 26-Apr-11 15:43pm

can u modify my coding made it works, because i hope can using my coding rather copy other people coding

Nish Nishant 26-Apr-11 15:44pm

I just changed your existing code. I did re-format it, that's all. But it is indeed your own code :-)

Albert Holguin 26-Apr-11 16:14pm

people here help you identify the problem, its up to you to fix your own code, don't abuse the help others are providing

Tarakeshwar Reddy 26-Apr-11 15:46pm

My 5

Nish Nishant 26-Apr-11 15:48pm

Thanks!

Jayfam 26-Apr-11 15:46pm

char* is? i not understand with char*, can you further explain?

Nish Nishant 26-Apr-11 15:49pm

A char represents a single character. C does not have a string type. In C, a string is represented by a char*. Pointer to character.

Jayfam 26-Apr-11 15:53pm

i got a error of old-style parameter declarations in prototyped function definition

Nish Nishant 26-Apr-11 15:56pm

I tried that code in VC++ 2010 and compiled as "C" (not C++). Code compiles fine.

Albert Holguin 26-Apr-11 16:16pm

this may be the print() instead of printf() type-o

Espen Harlinn 26-Apr-11 15:58pm

Nice reply, 5ed!

Nish Nishant 26-Apr-11 16:03pm

Thanks Espen!

Jayfam 26-Apr-11 16:12pm

thanks for the help, i finally understand and the problem solve

Nish Nishant 26-Apr-11 16:14pm

Glad to hear that, and you are most welcome.

Albert Holguin 26-Apr-11 16:17pm

accept a solution to close the question

Jayfam 26-Apr-11 16:18pm

accept already

NuttingCDEF · Accepted Answer · 2011-04-26T09:55:00

How about:

C#

char *m[MONTHS] = {"", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
    int i;
    printf("%s%13s\n", "Input", "output");
    for(i=1 ; i<xMONTHS ; i++){
        printf("%7d%13s\n", i, m[i]);
    }

1. In simple terms a string is a pointer to a char (OK I know that oversimplifies it, but the idea's roughly right) - so you need to get your declaration of 'm' right.

2. Arrays are zero based - so to use indices 1 to 12, you need the zero'th element as a dummy.

3. Your format strings need to reflect the fact that you are trying to print an integer and a string - not 2 chars.

4. You can't just print 'm' - you need to specify the element of the array.

5. New line characters in the format strings will make your output more readable - they need to be explicit and are not implied.

6. You might usefully get hold of a copy of Kernighan & Ritchie (http://en.wikipedia.org/wiki/The_C_Programming_Language[^]) which (at least when I got it) was the Bible for learning C (and any C-like) language.

7. Depending on your development environment you might also consider ditching functions like printf for the string safe counterparts like StringCchPrintf (http://msdn.microsoft.com/en-us/library/ms647466(VS.85).aspx[^]) that offer some protection against ubiquitous buffer overrun bugs beloved of hackers!

Declaration problem on C

3 solutions

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Declaration problem on C

3 solutions

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