QUESTION 51 · Input and output

Why should getchar’s return value be stored in int?

2 marks

Answer

getchar returns an int containing the character read, or EOF when input ends or an error occurs.

Store the result in int so that EOF can be distinguished from a character.
Test for EOF before using the result as a character.

Read the detailed 5-mark answer →

QUESTION 52 · Input and output

Explain character input/output and safe whole-line input in C.

5 marks

Answer in brief

Character input/output functions handle individual characters. Line input/output functions handle a string containing a line of text.

Character functions

getchar: Reads one character from standard input. Store its result in int so that the special end-of-input value EOF can be detected.
putchar: Writes one character to standard output. For example, putchar('A'); displays A.

Line functions

fgets: Reads at most one less than the supplied array size and adds a terminating null character when successful. It keeps the newline if it reads one.
puts: Writes a string and then adds a newline.
Header: Include stdio.h before using these functions.

Example

For char name[40];, fgets(name, sizeof name, stdin) reads a line into name if the call succeeds. It can store at most 39 input characters plus the terminating null character. If the line is longer, part of it remains unread. Check that the result is not NULL before using the line.

Important points

Check for EOF before treating a getchar result as a character. Do not use gets: it cannot limit the input size and has been removed from standard C. Functions such as getch from conio.h are not part of standard C. After numeric scanf input, a newline may remain; the next line read may read that newline. Plan the input sequence carefully.

Reference tables

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Character and line functions
Function	Purpose	Important detail
getchar()	Reads the next input character.	Returns int so it can represent an unsigned-char value or EOF.
putchar(ch)	Writes one character.	Use a character value, not a string pointer.
fgets(buffer, size, stdin)	Reads at most size − 1 characters.	On success, adds a null terminator; a read newline is retained.
puts(text)	Writes a string followed by a newline.	Do not add an unwanted second newline.

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Input requirements
Need	Suitable starting point	Extra responsibility
One next character	getchar	Handle EOF and any whitespace deliberately.
A bounded whole-line segment	fgets	Detect a missing newline if truncation matters.
A numeric token	Checked formatted input or checked text conversion	Validate success and representable range.

C program and output

Download .c Open compiler

/* CodeBhavya | PPS AR25 | Learning example */
#include <stdio.h>
int main(void)
{
    int ch = getchar();
    if (ch == EOF) {
        puts("No character received");
        return 1;
    }
    putchar(ch);
    putchar('\n');
    return 0;
}