C Library - getchar() function

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The C library getchar() function reads the next character from the standard input(stdin) and returns it as an unsigned char cast to an int. This function is commonly used for simple input tasks, such as reading characters one by one.

Syntax

Following is the C library syntax of the getchar() function −

int getchar(void);

Parameters

The getchar function does not take any parameters. It is invoked without arguments.

Return Value

The getchar function returns the next character from the standard input as an unsigned char cast to an int. If the end-of-file (EOF) is reached or if an error occurs, getchar returns EOF. The EOF is typically defined as -1 in the standard library.

Example 1: Reading a Single Character

This program reads a single character from the user and prints it to the screen.

Below is the illustration of C library getchar() function.

#include <stdio.h>

int main() {
   int ch;

   printf("Enter a character: ");
   ch = getchar();

   printf("You entered: %c\n", ch);

   return 0;
}

Output

The above code produces following result−

Enter a character: A
You entered: A

Example 2: Counting Vowels in Input

This program reads characters from the input until EOF is encountered and counts the number of vowels.

#include <stdio.h>

int main() {
   int ch;
   int vowels = 0;

   printf("Enter text (press Ctrl+D to end on UNIX or Ctrl+Z on Windows):\n");

   while ((ch = getchar()) != EOF) {
       if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' ||
           ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U') {
           vowels++;
       }
   }

   printf("Number of vowels: %d\n", vowels);

   return 0;
}

Output

After execution of above code, we get the following result

Enter text (press Ctrl+D to end on UNIX or Ctrl+Z on Windows):
Hello World
Number of vowels: 3