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-   -   Problem while populating structure (http://www.go4expert.com/forums/populating-structure-t12601/)

rajanandhini 31Jul2008 15:52

Problem while populating structure
 
Hi,

I need to populate a structure with the values from a string.I tried using strncpy but it did not work. Please let me know if any more details are required. Please find the below code and help me.
Code:

#include <stdio.h>
#include <string.h>

struct file
{
const char filename[2];
const char data[12];
const char data2[4];
};
struct file file1;

void main()
{
char a[25];
FILE *fp;

strcpy(a,"te this is test abcd");
strncpy(file1.filename,a,sizeof(file1));

fp=fopen(file1.filename,"w");
fwrite(file1.data,12,1,fp);
}

I need to populate the structure as:
filename:te
data:this is test
data2:abcd

Please help me
Thanks,
nan

xpi0t0s 31Jul2008 21:57

Re: Problem while populating structure
 
You need to allow space for the terminating NULLs. In C the string "te" is represented by the THREE characters 't', 'e' and 0. Most string functions depend on this, so while you CAN store 't' and 'e' in a char[2] you really need to know what you are doing.

Secondly you need to know what const means. It means something is a constant and can't be changed. So don't make stuff const that you want to change.

sizeof(file1) will give you the size of the structure, not the size of one of its elements.

ALWAYS clean up resources you allocate. This means you need an fclose somewhere.


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