How to use getc() in C++

The getc function is a C library function that reads the single character value from an input stream.

In order to use the getc function, the stdio header file needs to be included in the program, as shown below:

#include <stdio.h>

Parameters

The function takes in one parameter: a pointer to a file object that recognizes an input stream.

Return Value

Upon successful execution of the function, it returns the integer value, i.e., the ASCII value of the read character. In case of errors, End-of-File (EOF) is returned. If the EOF condition causes the failure, it sets the EOF indicator feof on stream; else, it sets the error indicator to ferror.

Example

The code below explains how the getc function works:

  1. The “demo.txt” file is opened.
  2. The getc function reads the single character from the file in each iteration of the loop.
  3. The returned value from the function is stored in the variable of type int.
  4. In line 15, the putchar function converts the integer to a character and prints the standard output.
  5. After the standard file reading loop, error handling takes over.
main.cpp
demo.txt
#include <iostream>
#include <stdlib.h>
using namespace std;
int main() {
  //file reading
  FILE* file = fopen("demo.txt", "r");
  int val;
  // standard C I/O file reading loop
  while (val = getc(file)) {
    // breaks from the loop if EOF 
    if (val == EOF)
      break;
    putchar(val);
    cout << endl; 
  }
  
  // In case of an error ferror indictor is set true
  if (ferror(file)) 
    cout << "Error during file reading" << endl;
  //In case when EOF is reached, then feof indicator is set true
  if (feof(file))
    cout << "Successful execution of function" << endl;
 
  
  return 0;
}

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