The difference between echo, print, var_dump () and print_r ()

The difference between 1.echo and print

What they have in common: first of all, echo and print are not strictly functions, they are both language structures; they can only output string, integer, and int floating-point data. Complex and resource-based data cannot be printed; the difference is that echo can output multiple variables in succession, while print can only output one variable at a time. The value printed by print can be copied directly to a variable, such as $a = print "abc123", while echo cannot, it does not behave like a function, so it cannot be used in the context of a function. When used, the echo () function is slightly faster than print ().

The difference between 2.var_dump () and print_r ()

What they have in common: both can print complex variables such as arrays and objects. Difference: print_r () can only print information that is easy to understand, and print_r () will move the pointer of the array to the end when printing the array, and use reset () to bring the pointer back to the beginning. Var_dump () can print not only the data of the compound type, but also the variables of the resource type. And the output information of var_dump () is more detailed, which is generally used in debugging.