typedef ... FILE;

FILE *fopen(char *name, char *mode);
int fscanf(FILE *inf, char *format, ...);
int sscanf(char *inf, char *format, ...);
char *fgets(char *buf, int bufsize, FILE *inf);
int fgetc(FILE *inf);
int getchar();
int fprintf(FILE *outf, char *format, ...);
int printf(char *format, ...);
int fputc(int ch, FILE *outf);
int putchar(in ch);
etc. etc. etc. etc. etc.