File Streams

Opening files

fopen

FILE *fopen(filename, "[rwa][+][b]")

    r  : Read text file
    w  : Write new text file
    a  : Append to new or existing text file
    +  : Read-write mode
    b  : Binary file

• Opens an IO stream for reading a file.
• Returns NULL for error.

Examples

FILE *hFile = fopen("input.dat", "r+b");
if (hFile != NULL) {
     ...
}

Reading files

getc

int getc(FILE *fp)

• Reads a character.
• Returns EOF for end-of-file or error.

fgets

char *fgets(char *line, int maxline, FILE *fp)

• Reads the entire current line, including the newline character.
• Returns at most maxline-1 characters plus an end-of-string character ('{content}').
• Returns NULL on end-of-file or error.

fscanf

int fscanf(FILE *fp, char *format, ...)

Writing files

putc

int putc(int ch, FILE *fp)

• Writes a character.
• Returns EOF for error.

fputs

int fputs(char *line, FILE *fp)

• Writes a string.
• Does not automatically add a newline character.
• Returns EOF for error, and zero for success.

fprintf

int fprintf(FILE *fp, char *format, ...)

Closing files

fclose

int fclose(FILE *fp)