File IO

Question 1

What are the functions that can be used to

1. read from stdin
2. output to the stdout

Single character at a time?

Answer 1

int getchar(void): can be used to read in a single character at a time from the stdin

int putchar(int c) can be used to output a single character at a time.

Question 2

What does getchar return?

Answer 2

getchar returns an EOF or an unsigned char

Question 3

What is the prototype for fopen and what does it return?

Answer 3

the prototype for fopen is

FILE* fopen (const char* fname, const char* mode);

It returns either:

• NULL, if the file doesn’t exist
• the handle/stream to the file.

Question 4

What are the different modes in which a file can be opened and what are the symbols?

Answer 4

The different modes are:

• r: read
• w: write
• a: append

Question 5

What is the prototype of fprintf and how does it work?

Answer 5

int fprintf (FILE* fp, char* format, ……);

It takes in a file pointer/handler and then writes the text along with the input data onto that file.

Question 6

Name the functions that can be used to write a character, and a string to a file.

Answer 6

Character: fputc(char c, FILE* fp);

String: fputs(char* str, FILE* fp);

Question 7

Name the functions that can be used to read a

1. character and also to read
2. A string of length n

Answer 7

char c = fgetc(fp);

fgets(s, n, fp);

where n is the maximum length to read, the read string will be stored inside the variable s

Question 8

gets vs fgets

Answer 8

gets: does not care about the size of the buffer and reads until a newline is found. The newline is not kept by gets.
fgets: reads from the file and stops when the maximum number of bytes are read, a newline character is found or the end of file is reached.

When fgets encounters a newline, it keeps it.

Question 9

puts vs fputs

Answer 9

puts adds an extra \n after printing

fputs does not