What are the Key Differences Between PHP's `print` and `echo` Statements?

The Subtle Differences Between PHP's print and echo

At first glance, PHP's print and echo appear as distinct constructs. However, they share a commonality at their core: the echo keyword. This duality stems from the internal source code, where both constructs invoke the same opcode for echoing output.

Key Distinctions:

• Return Value: print always returns 1, while echo does not.
• Syntax: print can handle only one expression, while echo can print multiple expressions.
• Precedence: echo is a statement, while print expr is an expression that can be used within other expressions.

Semantic Equivalence:

The statement echo e1, e2, ..., eN; can be understood as a shorthand for:

echo e1;
echo e2;
...;
echo eN;

Similarly, print e can be translated as:

echo (string) e;

Runtime Differences:

• print: Adds a single opcode to populate a temporary variable.
• echo: Compiles into a single opcode for one expression or multiple opcodes for multiple expressions.

Speed:

The performance difference between print x and echo x is negligible. When it comes to multiple expressions, echo a,b,c is faster than echo a.b.c.

Usage Recommendations:

In web applications where output is primarily concentrated in templates, using echo for both template and server-side output is a sensible choice. Echo also has the advantage of handling multiple expressions and not incurring the overhead of temporary variables.

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