Insertion of array to file error

Question

I use the following code to insert array of structure to file but it crash:

void SaveInFile(List * pl)
{

        int i;
        int s = ListSize(pl);

        file = fopen("myFile.txt", "w");        //3shan aktb 3la file mn gded 
        for (i = 0; i <= s; i++) {
                file = fopen("myFile.txt", "a");
                fprintf(file, "IDOfprocess%s/n", pl->entry[i].ID);
                fprintf(file, "IDOfprocess%s/n", pl->entry[i].BurstTime);
        }
        fclose(file);
}

Any idea how to solve this?

If ListSize returns the size N for list with N elements, then: for( i=0;i<=s;i++) → for( i=0;i<s;i++), otherwise you'll be getting segmentation fault. — Maroun
– Maroun, Commented Jan 8, 2014 at 14:33
You're calling fopen() inside the loop (i.e., for each entry). Remove the second fopen(). Also, what data types are ID and BurstTime? You are using %s which implies null-terminated string, so hopefully they are indeed strings. — cbranch
– cbranch, Commented Jan 8, 2014 at 14:35
1) fopen the file first in "a" mode, unless you want to "truncate" it, but anyway you can't open it s+1 time times, thus 2) remove fopen from inside the lloop — ShinTakezou
– ShinTakezou, Commented Jan 8, 2014 at 14:48
ouch... I bet you any money this will leak memory... calling fopen s times without fclose... don't do that oh, and check the FILE * returned by fopen, too. If it's NULL, something went wrong — Elias Van Ootegem
– Elias Van Ootegem, Commented Jan 8, 2014 at 15:13

HelloWorld123456789 · Accepted Answer · 2014-01-08 14:56:07Z

1

You are opening the file multiple times without closing it. This will do:

void SaveInFile(List* pl)
{

int i;
int s=ListSize(pl);

file=fopen("myFile.txt","w");//3shan aktb 3la file mn gded 
fclose(file);
for( i=0;i<=s;i++){

file=fopen("myFile.txt","a");
fprintf(file,"IDOfprocess%s/n",pl->entry[i].ID);
fprintf(file,"IDOfprocess%s/n",pl->entry[i].BurstTime);

fclose(file);
}
}

If you do not close the file, the content of any unwritten output buffer is not written to the file.

But what you should actually do is open the file one time and perform the append operations:

void SaveInFile(List* pl)
{

int i;
int s=ListSize(pl);

file=fopen("myFile.txt","w");//3shan aktb 3la file mn gded 
fclose(file);

file=fopen("myFile.txt","a");
for( i=0;i<=s;i++){

fprintf(file,"IDOfprocess%s/n",pl->entry[i].ID);
fprintf(file,"IDOfprocess%s/n",pl->entry[i].BurstTime);
}
fclose(file);
}

edited Jan 8, 2014 at 14:56

answered Jan 8, 2014 at 14:40

HelloWorld123456789

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2 Comments

fernando.reyes Over a year ago

You still need to close the first fopen or you have a resource leak... may be just comment it.

AMH Over a year ago

how to write new line as \n print the same charachter not new line

MOHAMED · Accepted Answer · 2014-01-08 14:38:00Z

1

your for loop is reaching s and you are starting from 0 (so you are treating s+1 elements and not s elements)

So it should be

for( i=0;i<s;i++){

answered Jan 8, 2014 at 14:38

MOHAMED

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