The Nuances of PHP's print and echo
Despite superficially appearing as distinct constructs, PHP's print and echo share a common underlying implementation - the echo handler. However, a deeper dive reveals subtle differences between the two that determine their usage and suitability in various scenarios.
Syntactical Differences
- print expr is an expression that evaluates to a value and can be used within larger expressions.
- echo expr is a statement that simply outputs the expression's value to an output buffer.
Semantic Differences
- print e evaluates and type-casts e to a string, then streams it to the output buffer and returns 1.
- echo e is equivalent to print e, but does not have a return value.
Runtime Considerations
- print incurs a slight overhead due to the need to populate a return variable.
- echo directly delegates the printing task to the echo handler without any additional overhead.
Syntax and Use Cases
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Syntax: print expr vs. echo expr, expr, ..., expr
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Use Cases:
- print is useful where a return value is needed, such as conditional expressions or obtaining an expression's result value.
- echo is better suited for simple output, as it supports multiple arguments and does not have a return value.
Which Construct to Use?
In web applications, it's common practice to use echo since templates typically leverage the = syntax, which is an alias of echo. Moreover, echo is more efficient when printing multiple expressions without concatenation and has a smaller runtime overhead. Therefore, echo is the preferred choice for most output tasks.
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