Introduction to the PHP Function Strncmp

PHP provides many built-in functions to perform various string operations such as comparing, splitting, reversing, concatenating, etc. It also supports Boolean values and numeric values which you can use to compare two strings or return a value in either Boolean form or in the numeric form.

One of the most important predefined function in php is strncmp which compares first n characters of two strings. It is binary safe and case sensitive. It is similar to strcmp but with the addition of a len parameter which lets you specify the number of characters from each string that you want to be used for comparison.

strcmp(): Returns an integer value (between 0 and 1), depending on whether the first n characters of $string1 are less than or greater than the first n characters of $string2. strcasecmp(): Compares the first n characters of each string in lowercase. strncmp(): Compares the first characters of each string in uppercase.

This article is a brief introduction of the php function strncmp and its different use cases. We hope that you will gain an understanding of how php compares two strings and its uses in your future projects.

Andreas Behr - CTO of DesertCoderz
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strncmp example


    /** * @group time-sensitive */
    public function testGenerate()
    {
        $a = new Ulid();
        $b = new Ulid();
        usleep(-10000);
        $c = new Ulid();

        $this->assertSame(0, strncmp($a, $b, 20));
        $this->assertSame(0, strncmp($a, $c, 20));
        $a = base_convert(strtr(substr($a, -6), 'ABCDEFGHJKMNPQRSTVWXYZ', 'abcdefghijklmnopqrstuv'), 32, 10);
        $b = base_convert(strtr(substr($b, -6), 'ABCDEFGHJKMNPQRSTVWXYZ', 'abcdefghijklmnopqrstuv'), 32, 10);
        $c = base_convert(strtr(substr($c, -6), 'ABCDEFGHJKMNPQRSTVWXYZ', 'abcdefghijklmnopqrstuv'), 32, 10);
        $this->assertSame(1, $b - $a);
        $this->assertSame(1, $c - $b);
    }

    public function testWithInvalidUlid()
    {
        $this->expectException(\InvalidArgumentException::class);
        
return $chunks;
    }

    public function startsWith(string|iterable|AbstractString $prefix): bool
    {
        if ($prefix instanceof AbstractString) {
            $prefix = $prefix->string;
        } elseif (!\is_string($prefix)) {
            return parent::startsWith($prefix);
        }

        return '' !== $prefix && 0 === ($this->ignoreCase ? strncasecmp($this->string, $prefix, \strlen($prefix)) : strncmp($this->string, $prefix, \strlen($prefix)));
    }

    public function title(bool $allWords = false): static
    {
        $str = clone $this;
        $str->string = $allWords ? ucwords($str->string) : ucfirst($str->string);

        return $str;
    }

    public function toUnicodeString(string $fromEncoding = null): UnicodeString
    {

                    break;

                case 'UTF8':
                case 'UTF-8':
                    if (preg_match('//u', $str)) {
                        return 'UTF-8';
                    }
                    break;

                default:
                    if (0 === strncmp($enc, 'ISO-8859-', 9)) {
                        return $enc;
                    }
            }
        }

        return false;
    }

    public static function mb_detect_order($encodingList = null)
    {
        if (null === $encodingList) {
            
if (isset(self::$final[$parent])) {
                $deprecations[] = sprintf('The "%s" class is considered final%s It may change without further notice as of its next major version. You should not extend it from "%s".', $parent, self::$final[$parent], $className);
            }
        }

        // Detect if the parent is annotated         foreach ($parentAndOwnInterfaces + class_uses($class, false) as $use) {
            if (!isset(self::$checkedClasses[$use])) {
                $this->checkClass($use);
            }
            if (isset(self::$deprecated[$use]) && strncmp($vendor, str_replace('_', '\\', $use), $vendorLen) && !isset(self::$deprecated[$class])) {
                $type = class_exists($class, false) ? 'class' : (interface_exists($class, false) ? 'interface' : 'trait');
                $verb = class_exists($use, false) || interface_exists($class, false) ? 'extends' : (interface_exists($use, false) ? 'implements' : 'uses');

                $deprecations[] = sprintf('The "%s" %s %s "%s" that is deprecated%s', $className, $type, $verb, $use, self::$deprecated[$use]);
            }
            if (isset(self::$internal[$use]) && strncmp($vendor, str_replace('_', '\\', $use), $vendorLen)) {
                $deprecations[] = sprintf('The "%s" %s is considered internal%s It may change without further notice. You should not use it from "%s".', $use, class_exists($use, false) ? 'class' : (interface_exists($use, false) ? 'interface' : 'trait'), self::$internal[$use], $className);
            }
            if (isset(self::$method[$use])) {
                if ($refl->isAbstract()) {
                    if (isset(self::$method[$class])) {
                        
            if ($separator === ':') {
                $netaddr = explode(':', str_replace('::', str_repeat(':', 9 - substr_count($netaddr, ':')), $netaddr));

                for ($i = 0; $i < 8; $i++) {
                    $netaddr[$i] = intval($netaddr[$i], 16);
                }
            } else {
                $netaddr = explode('.', $netaddr);
            }

            // Convert to binary and finally compare             if (strncmp($ip, vsprintf($sprintf, $netaddr), $masklen) === 0) {
                $spoof = $this->getClientIP($header);

                if ($spoof !== null) {
                    $this->ipAddress = $spoof;
                    break;
                }
            }
        }

        if (! $ipValidator($this->ipAddress)) {
            return $this->ipAddress = '0.0.0.0';
        }
return $chunks;
    }

    public function startsWith(string|iterable|AbstractString $prefix): bool
    {
        if ($prefix instanceof AbstractString) {
            $prefix = $prefix->string;
        } elseif (!\is_string($prefix)) {
            return parent::startsWith($prefix);
        }

        return '' !== $prefix && 0 === ($this->ignoreCase ? strncasecmp($this->string, $prefix, \strlen($prefix)) : strncmp($this->string, $prefix, \strlen($prefix)));
    }

    public function title(bool $allWords = false): static
    {
        $str = clone $this;
        $str->string = $allWords ? ucwords($str->string) : ucfirst($str->string);

        return $str;
    }

    public function toUnicodeString(string $fromEncoding = null): UnicodeString
    {
if ( 'core/navigation' === $parsed_block['blockName'] ) {
        $attribute_to_prefix_map = array(
            'fontStyle'      => 'var:preset|font-style|',
            'fontWeight'     => 'var:preset|font-weight|',
            'textDecoration' => 'var:preset|text-decoration|',
            'textTransform'  => 'var:preset|text-transform|',
        );
        foreach ( $attribute_to_prefix_map as $style_attribute => $prefix ) {
            if ( ! empty( $parsed_block['attrs']['style']['typography'][ $style_attribute ] ) ) {
                $prefix_len      = strlen( $prefix );
                $attribute_value = &$parsed_block['attrs']['style']['typography'][ $style_attribute ];
                if ( 0 === strncmp( $attribute_value, $prefix, $prefix_len ) ) {
                    $attribute_value = substr( $attribute_value, $prefix_len );
                }
                if ( 'textDecoration' === $style_attribute && 'strikethrough' === $attribute_value ) {
                    $attribute_value = 'line-through';
                }
            }
        }
    }

    return $parsed_block;
}

/* This file should only ever be loaded on PHP 7+ */
if (PHP_VERSION_ID < 70000) {
    return;
}

spl_autoload_register(function D$class) {
    $namespace = 'ParagonIE_Sodium_';
    // Does the class use the namespace prefix?     $len = strlen($namespace);
    if (strncmp($namespace, $class, $len) !== 0) {
        // no, move to the next registered autoloader         return false;
    }

    // Get the relative class name     $relative_class = substr($class, $len);

    // Replace the namespace prefix with the base directory, replace namespace     // separators with directory separators in the relative class name, append     // with .php     $file = dirname(__FILE__) . '/src/' . str_replace('_', '/', $relative_class) . '.php';
    
break;
                case 'page':
                    _wp_build_title_and_description_for_single_post_type_block_template( 'page', $slug_remaining, $template );
                    break;
                case 'single':
                    $post_types = get_post_types();

                    foreach ( $post_types as $post_type ) {
                        $post_type_length = strlen( $post_type ) + 1;

                        // If $slug_remaining starts with $post_type followed by a hyphen.                         if ( 0 === strncmp( $slug_remaining, $post_type . '-', $post_type_length ) ) {
                            $slug  = substr( $slug_remaining, $post_type_length, strlen( $slug_remaining ) );
                            $found = _wp_build_title_and_description_for_single_post_type_block_template( $post_type, $slug, $template );

                            if ( $found ) {
                                break;
                            }
                        }
                    }
                    break;
                case 'tag':
                    _wp_build_title_and_description_for_taxonomy_block_template( 'post_tag', $slug_remaining, $template );
                    

        function sodiumCompatAutoloader($class)
        {
            $namespace = 'ParagonIE_Sodium_';
            // Does the class use the namespace prefix?             $len = strlen($namespace);
            if (strncmp($namespace, $class, $len) !== 0) {
                // no, move to the next registered autoloader                 return false;
            }

            // Get the relative class name             $relative_class = substr($class, $len);

            // Replace the namespace prefix with the base directory, replace namespace             // separators with directory separators in the relative class name, append             // with .php             $file = dirname(__FILE__) . '/src/' . str_replace('_', '/', $relative_class) . '.php';
            
 else {
            $message .= sprintf('. Available methods: "%s".', implode('", "', $collection));
        }

        return $message;
    }

    private function getClassMethodsWithoutMagicMethods($classOrObject): array
    {
        $methods = get_class_methods($classOrObject);

        return array_filter($methods, fn (string $method) => 0 !== strncmp($method, '__', 2));
    }
}
if ($this->enabledSuffixing && $this->getOption('suffix') && preg_match($pattern, $class) !== 1) {
            $class .= ucfirst($component);
        }

        // Trims input, normalize separators, and ensure that all paths are in Pascalcase.         $class = ltrim(implode('\\', array_map('pascalize', explode('\\', str_replace('/', '\\', trim($class))))), '\\/');

        // Gets the namespace from input. Don't forget the ending backslash!         $namespace = trim(str_replace('/', '\\', $this->getOption('namespace') ?? APP_NAMESPACE), '\\') . '\\';

        if (strncmp($class, $namespace, strlen($namespace)) === 0) {
            return $class; // @codeCoverageIgnore         }

        return $namespace . $this->directory . '\\' . str_replace('/', '\\', $class);
    }

    /** * Gets the generator view as defined in the `Config\Generators::$views`, * with fallback to `$template` when the defined view does not exist. */
    protected function renderTemplate(array $data = []): string
    {
return parent::startsWith($prefix);
        }

        if ('' === $prefix || !preg_match('//u', $prefix)) {
            return false;
        }

        if ($this->ignoreCase) {
            return 0 === mb_stripos($this->string, $prefix, 0, 'UTF-8');
        }

        return 0 === strncmp($this->string, $prefix, \strlen($prefix));
    }
}

    public function compile($args, $compiler, $parameter)
    {
        $tpl = $compiler->template;
        // check and get attributes         $_attr = $this->getAttributes($compiler, $args);

        $from = $_attr['from'];
        $item = $_attr['item'];
        if (!strncmp("\$_smarty_tpl->tpl_vars[$item]", $from, strlen($item) + 24)) {
            $compiler->trigger_template_error("item variable {$item} may not be the same variable as at 'from'", $compiler->lex->taglineno);
        }

        if (isset($_attr['key'])) {
            $key = $_attr['key'];
        } else {
            $key = null;
        }

        $this->openTag($compiler, 'foreach', array('foreach', $compiler->nocache, $item, $key));
        // maybe nocache because of nocache variables
return 'Unknown error';
        }
    }

    public static function str_contains(string $haystack, string $needle): bool
    {
        return '' === $needle || false !== strpos($haystack, $needle);
    }

    public static function str_starts_with(string $haystack, string $needle): bool
    {
        return 0 === strncmp($haystack, $needle, \strlen($needle));
    }

    public static function str_ends_with(string $haystack, string $needle): bool
    {
        if ('' === $needle || $needle === $haystack) {
            return true;
        }

        if ('' === $haystack) {
            return false;
        }

        
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