PHP fgetc Function

last modified April 3, 2025

The PHP fgetc function reads a single character from a file pointer. It's useful for processing files character by character rather than line by line.

Basic Definition

The fgetc function reads one character at a time from an open file. It takes a file handle as its only parameter and returns the character.

Syntax: fgetc(resource $stream): string|false. The function returns the character as a string, or false on EOF or error. It's binary-safe.

Basic fgetc Example

This shows the simplest usage of fgetc to read a file character by character.

basic_fgetc.php

<?php

declare(strict_types=1);

$file = fopen('example.txt', 'r');
if ($file === false) {
    die('Error opening file');
}

while (($char = fgetc($file)) !== false) {
    echo $char;
}

fclose($file);

This opens a file and reads it character by character until EOF. Each character is echoed immediately. The loop continues until fgetc returns false.

Counting Specific Characters

This example counts how many times a specific character appears in a file.

count_chars.php

<?php

declare(strict_types=1);

function countCharInFile(string $filename, string $target): int {
    $file = fopen($filename, 'r');
    if ($file === false) {
        throw new RuntimeException("Could not open file");
    }
    
    $count = 0;
    while (($char = fgetc($file)) !== false) {
        if ($char === $target) {
            $count++;
        }
    }
    
    fclose($file);
    return $count;
}

$count = countCharInFile('example.txt', 'a');
echo "The letter 'a' appears $count times";

This demonstrates using fgetc for character analysis. The function counts occurrences of a specific character while reading the file sequentially.

Processing Binary Data

fgetc can read binary files one byte at a time.

binary_read.php

<?php

declare(strict_types=1);

$file = fopen('image.png', 'rb');
if ($file === false) {
    die('Error opening file');
}

$header = '';
for ($i = 0; $i < 8; $i++) {
    $char = fgetc($file);
    if ($char === false) break;
    $header .= sprintf('%02X ', ord($char));
}

fclose($file);
echo "PNG header bytes: $header";

This reads the first 8 bytes of a PNG file and displays them as hexadecimal. The 'rb' mode ensures proper binary reading on all platforms.

File Comparison Character by Character

This example compares two files character by character using fgetc.

file_compare.php

<?php

declare(strict_types=1);

function compareFiles(string $file1, string $file2): bool {
    $handle1 = fopen($file1, 'r');
    $handle2 = fopen($file2, 'r');
    
    if ($handle1 === false || $handle2 === false) {
        throw new RuntimeException("Could not open files");
    }
    
    $pos = 0;
    while (true) {
        $char1 = fgetc($handle1);
        $char2 = fgetc($handle2);
        
        if ($char1 === false && $char2 === false) {
            break; // Both files ended
        }
        
        if ($char1 !== $char2) {
            fclose($handle1);
            fclose($handle2);
            return false;
        }
        
        $pos++;
    }
    
    fclose($handle1);
    fclose($handle2);
    return true;
}

$result = compareFiles('file1.txt', 'file2.txt');
echo $result ? 'Files are identical' : 'Files differ';

This compares two files character by character. It returns false at the first difference or true if files are identical. The position counter tracks where files differ.

Reading Until Specific Character

This example reads a file until a specific delimiter character is found.

read_until.php

<?php

declare(strict_types=1);

function readUntil(string $filename, string $delimiter): string {
    $file = fopen($filename, 'r');
    if ($file === false) {
        throw new RuntimeException("Could not open file");
    }
    
    $result = '';
    while (($char = fgetc($file)) !== false) {
        if ($char === $delimiter) {
            break;
        }
        $result .= $char;
    }
    
    fclose($file);
    return $result;
}

$content = readUntil('data.txt', "\n");
echo "First line: $content";

This reads characters from a file until it encounters the specified delimiter. It's useful for parsing structured files where sections are separated by special characters.

Best Practices

Error Handling: Always check if fopen succeeds.
Resource Management: Close files with fclose when done.
Performance: For large files, consider buffered reading.
Binary Safety: Use 'rb' mode for binary files.
Memory: fgetc is memory efficient for large files.

Source

PHP fgetc Documentation

This tutorial covered the PHP fgetc function with practical examples showing its usage in different scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

List all PHP Filesystem Functions.

Ebooks