PHP String Functions (with Output)

Working with text

A lot of web work is about text — names, emails, messages, search terms. PHP gives you many ready-made string functions to measure, change, search and split text without writing loops yourself. Learn a handful of these and most text tasks become one line.

Length and case

<?php
  $t = "Coding Easily";
  echo strlen($t);        // 13  (number of characters)
  echo strtoupper($t);    // CODING EASILY
  echo strtolower($t);    // coding easily
  echo ucwords("hello world"); // Hello World
?>

strlen counts characters, strtoupper/strtolower change case, and ucwords capitalises the first letter of each word.

Search and replace

<?php
  $t = "I like PHP";
  echo str_replace("PHP", "MySQL", $t);   // I like MySQL
  echo strpos($t, "PHP");                  // 7 (position where PHP starts)
?>

str_replace swaps text; strpos tells you where a word starts (or returns false if not found). Because 0 is a valid position, check strpos with === false.

Trim and substring

<?php
  $name = "   Aman   ";
  echo trim($name);              // "Aman" (spaces removed)
  echo substr("CodingEasily", 0, 6);  // Coding
?>

trim removes stray spaces from both ends — essential for cleaning form input. substr pulls out a part: start at 0, take 6 characters.

explode and implode

These convert between a string and an array — very useful for CSV-like data.

<?php
  $csv = "apple,mango,banana";
  $arr = explode(",", $csv);   // ["apple","mango","banana"]
  echo $arr[1];                // mango

  $back = implode(" | ", $arr);
  echo $back;                  // apple | mango | banana
?>

explode splits a string into an array by a separator; implode joins an array back into a string. They are perfect opposites.

Common mistakes

• Forgetting positions start at 0. The first character is substr($t, 0, 1), not position 1.
• Checking strpos with ==. Since it can return 0 (a valid position), use === false to test "not found".
• Not trimming form input. Extra spaces cause failed logins and duplicate data.
• Mixing up explode and implode. explode makes an array; implode makes a string.

Summary

• strlen for length; strtoupper/strtolower/ucwords for case.
• str_replace to replace; strpos to find a position.
• trim cleans spaces; substr pulls out a part.
• explode splits to an array; implode joins to a string.
• Positions start at 0 — remember this for substr and strpos.

Next, store split results with arrays in PHP, or clean user input in form validation.