Article Recommendation for PHP eval () function

Suppose that there is a dictionary in Python as follows: x={' a ': ' The ' 2,3,4 ', ' B ': ' x={'} needs to be merged into: ' C ': ' 1,2,3,4 '} needs to do three things: 1. Converts a string to a numeric list of 2. Merge two lists and add a new key value of 3. Remove the repeating element 1th step through the usual function eval () can be done, the 2nd step need to add a key value and add elements, the 3rd step using the properties of set set can achieve the effect of deduplication, but finally need to convert the set set to list. The code is as follows: x={' a ': ' 2,3,4 ', ' B ': '}x[', ' C ']=list (Set (eval (x[' a ']) +eval (x[' B ']))) del x[' a ']

1. Use Python to merge dictionary key values and remove instance code for repeating elements

Summary: Suppose there is a dictionary in Python as follows: x={' a ': ' 2,3,4 ', ' B ': ' x={'} needs to be merged into: ' C ': ' 1,2,3,4 '} needs to do three things: 1. Converts a string to a numeric list of 2. Merge two lists and add a new key value of 3. Remove duplicate element 1th step through the usual function eval () can be done, 2nd step need to add a key value and add elements, 3rd step using the properties of Set set

2. The eval, with and catch of JavaScript spoofing and its performance problems

Summary: Normally, the scope chain of the execution period context is unchanged, so many students think that JavaScript has only lexical scopes (static scopes, scoped by the function declaration position when writing code) but there are several mechanisms that can cheat the lexical ones that are with (), Eval () There is also a catch statement for the Try-catch statement where with and eval we should not go to use (which can cause a lot of problems) the deceptive lexical meaning is that the scope chain is modified at run time.

3. The SetTimeout secret that JavaScript developers should know

Summary: Timer settimeout is a common use that is used to call a function or evaluate an expression after a specified number of milliseconds. Syntax: SetTimeout (code, millisec, args); Note: If code is a string, it is equivalent to executing the eval () method to execute code. Of course, this article does not just tell you how to use settimeout, but also how it is implemented. 1, settimeout principle first look at a

4. Three ways to parse JSON data in JavaScript

Introduction: This article mainly introduces three methods of parsing JSON data in JavaScript, this article explains the eval () method, the new function method, the Json.parse () method and so on three kinds of methods, the need of friends can refer to the following

5. Python built-in functions--repr & STR

Summary: This is consistent with the results obtained through conversion (anti-quote "). As a normal function, this operation can be used in some cases to be useful. For most types, this function attempts to return a string that, when passed to Eval (), produces the same object,

6. Python built-in function--compile

Introduction: This function is used to compile a string of source code, the result can be generated bytecode or AST (like syntax tree), bytecode can be executed using function exec (), and AST can use Eval () to continue compiling. 2. The parameter source is a string of source code, or an AST object array.

7. How PHP disables the eval () function instance

Summary: In PHP, Eval is a function and cannot be directly disabled, but the Eval function is quite dangerous and often there are some problems, today we will look at the Eval function array operation and PHP how to disable the eval () function, the need for friends can refer to the following

8. PHP eval function use PHP in the eval () function tips

Summary: This function can take the value of a variable in a string and is typically used to manipulate the data on the database

9. About PHP eval () function definition and usage

Introduction: The following small series for everyone to bring a brief talk about the PHP eval () function definition and usage. Small series feel very good, now share to everyone, also for everyone to make a reference. Let's take a look at it with a little knitting.

How PHP disables the eval () function instance detailed _php instance

Summary: In PHP, Eval is a function and cannot be directly disabled, but the Eval function is quite dangerous and often there are some problems, today we will look at the Eval function array operation and PHP how to disable the eval () function, the need for friends can refer to the following

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