Integers not writing to file in C

Question

The following code runs fine, except my output file does not contain the integer 10, but instead the characters ^@^@^@ when I open it up in VIM. If I open it in textedit (on the mac) the file appears to be empty.

Does anybody know where I am going wrong here?

#include <stdio.h>
#include <stdlib.h>

#define MAX_LINE 256
#define MAX_NAME 30

int main() {
   FILE *fp;
   char fname[MAX_NAME] = "test1.dat"; 
   int x =10;
   int num= 0;

   if( (fp =fopen(fname, "w")) == NULL) {
      printf("\n fopen failed - could not open file : %s\n", fname);
      exit(EXIT_SUCCESS);
   }

   num= fwrite(&x, sizeof(int), 1, fp);
   printf("\n Total number of bytes written to the file = %d\n", num);

   fclose(fp);

   return(EXIT_SUCCESS);
}

Answer 1

You're writing binary data and expecting to see ASCII.

You could write the number in ASCII using fprintf : fprintf(fp, "%d", x)

Answer 2

Your code is writing the binary representation of the four bytes 0x0000000a to the file, ie ^@^@^@\\n

To write in ASCII, use fprintf instead.

Answer 3

You wrote the binary bytes of the integer to your file, so that's what you've got.

If you want to see a textual '1', use sprintf . Binary files often look empty or strange in text editors.

Answer 4

You're writing binary data and expecting ASCII?

If you wish to write formatted data, you can use eg the fprintf() function instead of fwrite().

Answer 5

您正在以二进制形式打开文件，因此基本上是在编写ascii字符10，而不是数字10。根据您要执行的操作，可以在文本模式下打开文件，请使用fprintf ...