Thread: hi i am new plz help me

i attached the code below
The i/p txt file is like this
939,MUM,ord,396,2,3.0,4.0
100,bom,nru,1009,10,4.0,6.0

and i want to add 3.0+4.0=7.0
i.e
First i want to read the txt file add last two columns writing it into another txt I written the code and i run the code i am getting
------------------------------------
939,MUM,ord,396,2,3.0,4.0
100,bom,nru,1009,10,4.0,6.0

Segmentation fault(coredump)
----------------------------------------------

please help me in this

Thanks & regards
vijay

1. Learn to indent code, eg.

Code:

#include<stdio.h>
void main()
{
    char temp[10];
    FILE *input1 = NULL;
    FILE *input2 = NULL;
    unsigned char buffer[100], lTempData[7][20];
    char *lPtr = NULL;
    int i =0;
    input1 = fopen("/u/n073313/vijay/File.txt", "rb");

    fread(buffer, 1,100, input1);
    {
        printf("First line %s\n",buffer);
        lPtr = strtok(buffer, ",");

        strncpy(lTempData[i], lPtr, strlen(lPtr));

        while (lPtr != NULL)
        {
            i++;
            strncpy(lTempData[i], lPtr, strlen(lPtr));
        }

        for (int j =0; j< 7 ; j++)
            printf("Values %s\n", lTempData[i]);

        int a = atol(lTempData[5]);
        int b = atol(lTempData[6]);

        int c = a+b;

        printf("Values %d %d result %d\n", a, b, c);
        sprintf(temp, "%d", c);
        input2 = fopen("File2.txt", "r");
        fwrite(c, 1, 10, input2);
        fclose(input1);
        fclose(input2);

    }

}

2. main returns int, not void.

3. using fread to read a text file is very poor.
a) it won't stop at a newline
b) it won't have a \0, for the benefit of the following string functions
c) it should have been in a loop, if you want to process the whole file.

Code:

while ( fgets( buffer, sizeof buffer, input1 ) != NULL ) {
  // do stuff with each line
}

4. strncpy(lTempData[i], lPtr, strlen(lPtr));
It's nice that you're using strncpy to protect your strings from overflow, but
a) you should use the size of the destination, not the size of the source
b) you also need to ensure a \0 is copied (strncpy doesn't always do this).

5. while (lPtr != NULL)
What changed lPtr in this loop?
If it gets into the loop, it's not getting out anytime soon.

1) You did not make the changes Salem requested. You have not indented the code and main still return void, not int as it should be!
2) If you don't mind, point out on what lines the error occurs!

Line 15:

Code:

lPtr = strtok(buffer, ",");

Perhaps you are missing the prototype for strtok?


Line 36 is this:

Code:

	fwrite(c, 1, 10, input2);

Since 'c' is an integer, not the address of the data you want to write, I'm not at all surprised. Also, you are trying to write 10 items of 1 byte each - an integer is not 10 bytes in any architecture I know of.

--
Mats

Code:

fread(buffer, 1,100, input1);
{
printf("First line %s\n",buffer);
lPtr = strtok(buffer, ",");

Who said that after fread the buffer is nul-terminated?
and you are using functions that will work correctly only on the nul-terminated strings

Ok, so you have change void main to int main, which is correct change, but it's not one of the more important ones - it certainly won't fix the errors/warnings you are seeing. I suggested what those are caused by.

You are reading using fgets, but:

Code:

fread(buffer, 1,100, input1);

what is this line doing?


--
Mats