Classic introduction to PHP string operations

• Chapter1 String basics
• 1-1 The difference between single quotes and double quotes when declaring strings
• 1-2 The difference and connection between the grammatical structures of heredoc and nowdoc
• 1-3 heredoc and nowdoc initialize local variables and class attributes
• 1-4 Detailed explanation of two syntaxes and examples of variable parsing
• 1-5 String addition, deletion, modification and search operations
• Chapter2 In-depth explanation of string functions
• 2-1 Substring processing substr and related functions
• 2-2 String retrieval functions strpos() and strstr()
• 2-3 String padding and replacement str_pad() and str_replace()
• 2-4 String length statistics strlen() and mb_strlen(), mb_strwidth()
• 2-5 Splitting and combining strings explode() and implode()
• 2-6 Detailed explanation of character type conversion [temporary/permanent/automatic]
• 2-7 String formatting function [Key points]
• 2-8 String content filtering and transcoding
• 2-9 String serialization and JSON processing [Key points]