Write to file in C - c

Question

I'm having trouble transferring data from a file to another file using C, and I would like some help from the community to help me troubleshoot some of the output problems. I'm doing this because I want to convert the txt data into binary data next. Totally testing purpose.
Here is the code I have so far:
int txt2txt()
{
FILE *pTextFile, *pBinaryFile;
char buffer[1000];
pTextFile = fopen ("AS001.txt","r");
pBinaryFile = fopen("BS001.txt","w");
while(fgets(buffer,1000,pTextFile)!=NULL){
fwrite(buffer,sizeof(int),sizeof(buffer),pBinaryFile);
}
fclose(pTextFile);
fclose(pBinaryFile);
return 0;
}
Sample input/output:
AS001.txt:
91829812
1231231
1231232
123231123
1232312
123123123
12312312
and output BS001.txt:
91829812
„w O]€©O] * + O] ¤O]H¨O] ¬O]( O] #¨O]Lü( ¾8„w8O]š8„w¥ex O]ˆ©O] O]8¤O]  ¤O] ¤O]H¨O]`žO]H O] 8¤O]œü( ¾8„w8O]š8„wuex O]#¤O] ЪO]Q ø H¨O]PO] ¬O] O]PO]™Qº€O]PO] D Q Q ¬O] Q ˆ p¨O] ¬O]Õqˆw¹Qºþÿÿÿ|O]

Answer 1

This code:
while(fgets(buffer,1000,pTextFile)!=NULL){
fwrite(buffer,sizeof(int),sizeof(buffer),pBinaryFile);
}
Tries to read 1000 bytes and then writes 1000 * sizeof(int) bytes per iteration. Unless your system has 1-byte integers (unlikely), that's probably not what you wanted.
Besides that, fgets might not have filled up your entire buffer - it stops at a newline.
Use:
while (fgets(buffer, 1000, pTextFile) != NULL)
{
fwrite(buffer, 1, strlen(buffer), pBinaryFile);
}
Edit: Since you're having problems, here's a complete example. First, source code:
#include <stdio.h>
#include <string.h>
int main(void)
{
char buffer[1000];
FILE *pTextFile = fopen("AS001.txt","r");
FILE *pBinaryFile = fopen("BS001.txt","w");
while (fgets(buffer, 1000, pTextFile) != NULL)
{
fwrite(buffer, 1, strlen(buffer), pBinaryFile);
}
fclose(pTextFile);
fclose(pBinaryFile);
return 0;
}
Second, build & run:
$ make example
cc example.c -o example
$ cat AS001.txt
91829812
1231231
1231232
123231123
1232312
123123123
12312312
$ ./example
$ diff AS001.txt BS001.txt
$

Answer 2

Include the string.h from the standard library and change your write command to this:
fwrite(buffer, sizeof(char), strlen(buffer), pBinaryFile);
This will stop it from trying to write the junk data in the rest of the buffer, which is undefined.