COMPARES two STRINGS of the first n characters by the case-sensitive way.
<?php
int strncmp ( str $str1 , str $str2 , int $len )
where,
$str1 = The first STRING to compare
$str2 = The second STRING to compare
$len = Number of characters to br used in the comparison
?>
EXERCISE
<?php
function str_ncmpN ($par1, $par2, $par3)
{
if (strncmp($par1, $par2, $par3) > 0)
{
echo 'Returned value: ' . strncmp($par1, $par2, $par3) .
'<br>thefore,<br>' . substr($par1, 0, $par3) .
'<br>is GREATER than<br>' . substr($par2, 0, $par3);
}
elseif (strncmp($par1, $par2, $par3) < 0)
{
echo 'Returned value: ' . strncmp($par1, $par2, $par3) .
'<br>thefore,<br>' . substr($par1, 0, $par3) .
'<br>is LESS than<br>' . substr($par2, 0, $par3);
}
else
{
echo 'Returned value: ' . strncmp($par1, $par2, $par3) .
'<br>thefore,<br>' . substr($par1, 0, $par3) .
'<br>is EQUAL to<br>' . substr($par2, 0, $par3);
}
}
$srcnm01 = 'Ad augusta per angusta';
$srcnm02 = 'Ad augusta per angusta';
$srcnm03 = 'angusta';
$intlen = 10;
// 10 initial characters
str_ncmpN($srcnm01, $srcnm02, $intlen);
echo '<br><br>';
str_ncmpN($srcnm01, $srcnm03, $intlen);
echo '<br><br>';
str_ncmpN($srcnm03, $srcnm01, $intlen);
?>
EXERCISE
<?php
function str_ncmp ($par1, $par2, $par3)
{
if (strncmp($par1, $par2, $par3) > 0)
{
echo 'Returned value: ' . strncmp($par1, $par2, $par3) .
'<br>thefore,<br>' . substr($par1, 0, $par3) .
'<br>is GREATER than<br>' . substr($par2, 0, $par3);
}
elseif (strncmp($par1, $par2, $par3) < 0)
{
echo 'Returned value: ' . strncmp($par1, $par2, $par3) .
'<br>thefore,<br>' . substr($par1, 0, $par3) .
'<br>is LESS than<br>' . substr($par2, 0, $par3);
}
else
{
echo 'Returned value: ' . strncmp($par1, $par2, $par3) .
'<br>thefore,<br>' . substr($par1, 0, $par3) .
'<br>is EQUAL to<br>' . substr($par2, 0, $par3);
}
}
$srcnm01 = 'Ad augusta per angusta';
$srcnm02 = 'AD AUGUSTA PER ANGUSTA';
$srcnm03 = 'angusta';
$intlen = 10;
// 10 initial characters
str_ncmp($srcnm01, $srcnm02, $intlen);
echo '<br><br>';
str_ncmp($srcnm01, $srcnm03, $intlen);
echo '<br><br>';
str_ncmp($srcnm03, $srcnm01, $intlen);
?>
EXERCISE
<?php
echo "Testing strncmp() function:
basic functionality.<br>";
echo "<br><br>Testing strncmp()
with single quoted string:<br>";
$var01 = 'Hello';
$var02 = 'Hi';
$var01a = "Hello";
$var02a = "Hi";
echo "After: strncmp('$var01a', '$var01a', 5)<br>";
var_dump( strncmp($var01, $var01, 5) );
//expected: int(0)
echo '<br><br>';
echo "After: strncmp('$var01a', '$var02a', 5)<br>";
var_dump( strncmp($var01, $var02, 5) );
//expected: value < 0
echo '<br><br>';
echo "After: strncmp('$var02a', '$var01a', 5)<br>";
var_dump( strncmp($var02, $var01, 5) );
//expected: value > 0
echo "<br><br><br>Testing strncmp()
with double quoted string:<br><br>";
echo "After: strncmp(\"$var01a\", \"$var01a\", 5)<br>";
var_dump( strncmp($var01a, $var01a, 5) );
//expected: int(0)
echo '<br><br>';
echo "After: strncmp(\"$var01a\", \"$var02a\", 5)<br>";
var_dump( strncmp($var01a, $var02a, 5) );
//expected: value < 0
echo '<br><br>';
echo "After: strncmp(\"$var02a\", \"$var01a\", 5)<br>";
var_dump( strncmp($var02a, $var01a, 5) );
//expected: value > 0
echo "<br><br><br>Testing strncmp()
with here-doc string:<br><br>";
$str = <<<HEREDOC
Hello
HEREDOC;
echo "After: strncmp(\"$str\", \"$var01a\", 5)<br>";
var_dump( strncmp($str, $var01a, 5) );
//expected: int(0)
echo "<br><br>After: strncmp(\"$str\", \"$var02a\", 5)<br>";
var_dump( strncmp($str, $var02a, 5) );
//expected: value < 0
echo "<br><br>After: strncmp(\"$var02a\",\"$str\", 5)<br>";
var_dump( strncmp($var02a, $str, 5) );
//expected: value > 0
?>
EXERCISE
<?php
/* Test strncmp() function with
* upper-case and lower-case alphabets
* as inputs for 'str1' and 'str2' */
echo "Test strncmp() function: with alphabets.";
echo "<br><br>Passing upper-case letters for 'str1':<br>";
for($ASCII = 65; $ASCII <= 90; $ASCII++) {
echo "After: strncmp( chr($ASCII), chr($ASCII), 1 )<br>";
var_dump( strncmp( chr($ASCII), chr($ASCII), 1 ) );
//comparing uppercase letters with
//uppercase letters; exp: int(0)
echo "<br>After:
strncmp( chr($ASCII), chr($ASCII + 32), 1 )<br>";
var_dump( strncmp( chr($ASCII), chr($ASCII + 32), 1 ) );
//comparing uppercase letters with
//lowercase letters; exp: value < 0
echo '<br>';
}
echo "<br><br>Passing lower-case letters for 'str1':<br>";
for($ASCII = 97; $ASCII <= 122; $ASCII++) {
echo "After: strncmp( chr($ASCII), chr($ASCII), 1 )<br>";
var_dump( strncmp( chr($ASCII), chr($ASCII), 1 ) );
//comparing lowercase letters with
//lowercase letters; exp: int(0)
echo "<br>After:
strncmp( chr($ASCII), chr($ASCII - 32), 1 )<br>";
var_dump( strncmp( chr($ASCII), chr($ASCII - 32), 1 ) );
//comparing lowercase letters with
//uppercase letters; exp: value > 0
echo '<br>';
}
?>
EXERCISE
<?php
/* Test strncmp() function with
* double quoted strings for
* 'str1', 'str2' */
echo "Test strncmp() function: with double quoted strings.<br>";
$strings = [
"Hello, World",
"hello, world",
"HELLO, WORLD",
"Hello, World\n",
"Hello".chr(0)."World"
];
/* loop through to compare each string
with the other string */
$count = 1;
for($index1 = 0; $index1 < count($strings); $index1++) {
echo "<br><br>Iteration: $count<br>";
for($index2 = 0; $index2 < count($strings); $index2++) {
var_dump( strncmp( $strings[$index1],
$strings[$index2],
(strlen($strings[$index1]) + 1) ) );
echo '<br>';
}
$count ++;
}
?>
EXERCISE
<?php
/* Test strncmp() with various lengths */
echo "Test strncmp() function:
with different lengths.<br><br>";
/* definitions of required variables */
$str1 = "Hello, World\n";
$str2 = "Hello, world\n";
/* loop through to compare the strings,
for various length values */
for($len = strlen($str1); $len >= 0; $len--) {
echo "After: strncmp($str1, $str2, $len)<br>";
var_dump( strncmp($str1, $str2, $len) );
echo '<br>';
}
?>
EXERCISE
<?php
/* Test strncmp() function with
* binary values passed to 'str1' & 'str2'
* and with the null terminated strings */
echo "Test strncmp() function:
Checking with the null terminated strings.<br><br>";
/* A binary function should not expect
* a null terminated string, and it
* should treat input as a raw stream of data */
$str1 = "Hello\0world";
$str2 = "Hello\0";
echo "After: strncmp(\"$str1\", \"$str2\", 12)<br>";
var_dump( strncmp($str1, $str2, 12) );
//expected: int(5);
?>
EXERCISE
<?php
/* Test strncmp() function with single
quoted strings for 'str1', 'str2' */
echo "Test strncmp() function: with single quoted strings.<br>";
$strings = array(
'Hello, World',
'hello, world',
'HELLO, WORLD',
'Hello, World\n'
);
/* loop through to compare each string
with the other string */
$count = 1;
for($index1 = 0; $index1 < count($strings); $index1++) {
echo "<br><br>Iteration: $count<br>";
for($index2 = 0; $index2 < count($strings); $index2++) {
var_dump( strncmp( $strings[$index1],
$strings[$index2],
(strlen($strings[$index1]) + 1) ) );
echo '<br>';
}
$count ++;
}
?>
EXERCISE
<?php
/* Test strncmp() function with
* different strings for
* 'str1', 'str2' and
* considering case sensitive */
echo "Test strncmp() function:
with different input strings.<br><br>";
/* heredoc string */
$str1 = <<<EOD
Example of string
spanning multiple lines
using heredoc syntax.
EOD;
/* identifier name contains underscore */
$str2 = <<<identifier_str2
Example of heredoc
string, whose identifier
having underscore("_")
& numeric value.
identifier_str2;
/* identifier name starts with underscore */
$str3 = <<<_identifier_str3
Hello, World
hello, world
_identifier_str3;
/* string containing control characters */
$str4 = <<<identifier_str4
Hello, World\n
Hello\0World
identifier_str4;
$strings = array(
$str1,
$str2,
$str3,
$str4
);
/* loop through to compare
each string with the other string */
$count = 1;
for($index1 = 0; $index1 < count($strings); $index1++) {
var_dump( strncmp( $strings[$index1],
$strings[$index1],
strlen($strings[$index1]) ) );
echo '<br>';
$count ++;
}
?>
EXERCISE
<?php
/* Test strncmp() function with
* more/less number of args
* and invalid args */
echo "Testing strncmp() function:
error conditions.<br><br>";
$str1 = 'string_val';
$str2 = 'string_val';
/* Invalid argument for $len */
$len = -8;
try {
var_dump( strncmp($str1, $str2, $len) );
} catch (\ValueError $e) {
echo $e->getMessage() . \PHP_EOL;
}
?>