I/O to and from files in C Programming Language

I/O to and from files

Similar statements also exist for handling I/O to and from files. The statements are

#include <>

FILE *fp;
    
fp = fopen(name, mode);

fscanf(fp, "format string", variable list);
fprintf(fp, "format string", variable list);

fclose(fp );

The logic here is that the code must

• define a local ``pointer'' of type FILE (note that the uppercase is necessary here), which is defined in <>
• ``open'' the file and associate it with the local pointer via fopen
• perform the I/O operations using fscanf and fprintf
• disconnect the file from the task with fclose

The ``mode'' argument in the fopen specifies the purpose/positioning in opening the file: ``r'' for reading, ``w'' for writing, and ``a'' for appending to the file. Try the following:

#include <>

void main()
{
FILE *fp;
int i;

fp = fopen("foo.dat", "w");        /* open foo.dat for writing */

fprintf(fp, "\nSample Code\n\n");  /* write some info */
for (i = 1; i <= 10 ; i++)  fprintf(fp, "i = %d\n", i);     fclose(fp);          /* close the file  */ }