fscanf in loop

well i am having a strange problem it goes as like this

Code:

---

//for(int i=1;i<n+1;i++);
        fscanf(fp,"%d %s",&e[1].p_len,e[1].data);
        cout<<e[1].p_len<<e[1].data;
/*        for( i=1;i<n+1;i++)
                printf("%d %s",e[i].p_len,e[i].data)*/

---

the above code works fine but when i do this that is applying the loop on fscanf

Code:

---

for(int i=1;i<n+1;i++);
        fscanf(fp,"%d %s",&e[i].p_len,e[i].data);
        cout<<e[1].p_len<<e[1].data;
/*        for( i=1;i<n+1;i++)
                printf("%d %s",e[i].p_len,e[i].data)*/

---

i get segmentation fault error

my entire code is here

Code:

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struct extract
{
        int p_num;
        int p_len;
        char data[100];
};
using namespace std;
int main (int argc , char *argv[]){
        FILE *fp;
        struct extract *e;
        int n,i;
        fp=fopen("data.raw","r");
        fscanf(fp,"%d",&n);
        e = new extract[n+1];
        e[0].p_num=n;
        cout<<n;
        for(int i=1;i<n+1;i++);
        fscanf(fp,"%d %s",&e[i].p_len,e[i].data);
        cout<<e[1].p_len<<e[1].data;
/*        for( i=1;i<n+1;i++)
                printf("%d %s",e[i].p_len,e[i].data)*/
        return 0;
}

---

thanks in advance...

You are missing a "&" operator in the fscanf call. You need to pass the address of the variable to which the data is to be stored, not the variable itself.

You have this:

Code:

---

fscanf(fp,"%d %s",&e[i].p_len,e[i].data);

---

You need this:

Code:

---

fscanf(fp,"%d %s",&e[i].p_len,&e[i].data);

---

Edit:
btw, your code is a little confusing since it contains elements of C and C++ (the cout statements are C++). As a general rule, it's best to stick to one or the other when you write a program.

Quote:

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Originally Posted by Swarvy

You are missing a "&" operator in the fscanf call. You need to pass the address of the variable to which the data is to be stored, not the variable itself.

You have this:

Code:

---

fscanf(fp,"%d %s",&e[i].p_len,e[i].data);

---

You need this:

Code:

---

fscanf(fp,"%d %s",&e[i].p_len,&e[i].data);

---

---

No use swarvy it is the same even if i add '&' before it.. i get the same error during the run time..
thanks for the reply anyhow

> for(int i=1;i<n+1;i++);
1. The local i is different from your global i (which remains uninitialised)
2. The ; at the end means this loop does nothing.

> fscanf(fp,"&#37;d %s",&e[i].p_len,e[i].data);
This does on the other hand use the aforementioned uninitialised i, and trashes some random location.
You were doing better in your other post.

Quote:

---

Originally Posted by Salem

> for(int i=1;i<n+1;i++);
1. The local i is different from your global i (which remains uninitialised)
2. The ; at the end means this loop does nothing.

> fscanf(fp,"%d %s",&e[i].p_len,e[i].data);
This does on the other hand use the aforementioned uninitialised i, and trashes some random location.
You were doing better in your other post.

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thanks salem....

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how could i be so foolish to oversee a small mistake