The difference between include( and require( in php

The difference between include() and require() in PHP: when the file is not found: require() triggers a fatal error, and include() triggers a warning. Efficiency: require() is generally less efficient than include(). Semantics: require() indicates that the file is required, include() indicates that the file is not required. Execution order: require() executes included files immediately, include() only executes when needed. Usage scenarios: Use require() for critical files to ensure loading, and include() for non-critical files to allow execution to continue when the file does not exist.

The difference between include() and require() in PHP

Core differences:

<code class="php">require(): 找不到文件时触发致命错误
include(): 找不到文件时触发警告</code>

Detailed description:

include() and require() are both functions in PHP used to include external files. The main difference is how errors are handled.

require():

• If the specified external file does not exist, a fatal error will be triggered, causing the script to abort execution.
• For critical files, require() must be used to ensure that the file can be loaded correctly.

include():

• If the specified external file does not exist, a warning will be triggered, but the script will continue execution.
• For non-critical files, you can use include() because the script can continue to run even if the file does not exist.

Other differences:

• Efficiency: require() is generally less efficient than include() because it runs Files are loaded dynamically while include() is pre-parsed at compile time.
• Semantics: require() indicates that the included file is necessary for the execution of the script, while include() implies that the file is not necessary for the script to run.
• Execution order: require() will execute the included file immediately, while include() will only execute when needed.

Usage scenarios:

• Key files: Use require() to ensure that the file exists and is loaded correctly. For example, include database connection files.
• Non-critical files: Use include() to still allow the script to continue running if the file does not exist. For example, include helper functions or style sheets.

Conclusion:

Choose to use require() or include() depending on the criticality of the file and the desired behavior. For required files, use require() to ensure their correct loading, and for non-required files, use include() to allow the script to continue running if the file does not exist.

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