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There are cases when we want to format strings which will help us to print the output in a particular format.When we use the string.format() function it returns a formatted version of its variable number of arguments following the description given by its first argument, the so-called format string.The format string that we get the output, is similar to those of the printf function of standard C: It is composed of regular text and directives, which control where and how each argument must be placed in the formatted string.Syntaxstring.format(“s = %a”)The string.format() syntax above contains an identifier s which is ... Read More
string.find() is one of the most powerful library functions that is present inside the string library.Lua doesn’t use the POSIX regular expression for pattern matching, as the implementation of the same takes 4, 000 lines of code, which is actually bigger than all the Lua standard libraries together. In place of the POSIX pattern matching, the Lua’s implementation of pattern matching takes less than 500 lines.The string.find() function is used to find a specific pattern in a given string, it normally takes two arguments, the first argument being the string in which the pattern we are trying to search, and ... Read More
There are so many scenarios where you might want to convert a decimal value into a character representation. The character representation of a decimal or integer value is nothing but the character value, which one can interpret using the ASCII table.In Lua, to convert a decimal value to its internal character value we make use of the string.char() function.Syntaxstring.char(I)In the above syntax, the identifier I represents the decimal value which we want to convert into a character.ExampleLet’s consider a very simple example, where you are given different decimal values, and you want to convert them to a character value.Consider the ... Read More
The string.byte() function is one of the most widely used Lua string library functions that takes a character or a string as an argument and then converts that character into its internal numeric representations.The character to internal numeric representations can be easily interpreted from the ASCII table.Syntaxstring.byte(ch) or string.byte(ch, idx)In the above representation of the string.byte() function, the ch identifier represents the character that we want to convert into a decimal value. Also, the idx identifier represents a character at that index of the string passed as an argument.Let’s consider a few examples where we will make use of the ... Read More
One of the most used functions in Lua is the sort function which is provided by the Lua library which tables a table as an argument and sorts the values that are present inside the table.The sort function also takes one more argument with the table and that argument is a function which is known as the order function. This order function is used to provide the logic if we want to sort the elements of the table in a certain order.The order function takes two arguments, and these two arguments must return true if the first argument should come ... Read More
There are very few sections we will explore the possibility of making use of a semicolon in Lua. Majority of the code doesn’t require it, while there are some cases where we might need them.ExampleLet’s consider a case where the use of semicolon seems necessary. Consider the example shown below − Live Demolocal a, b=10, 20 print(a+b)The above statement in Lua is perfectly valid and it works like a charm.Output30ExampleWhat if we change the code above and put it in the same line? Would it still be a valid Lua code? Let’s try it out. Consider the code shown below −local ... Read More
The select function in Lua is used to return the number of arguments that are passed into it as an argument. It can be used in two forms, the first one includes passing an index and then it will return the numbers that are passed after that number into the function as an argument in a list format, the other pattern is if we pass the length operator as a first argument, in that case it simply returns a count of the multiple arguments that are provided.ExampleLet’s explore both the cases in the examples shown below.Case 1 Live Demoprint(select(1, "a", "b", ... Read More
While working with tables, we can easily access and modify the values present in the tables provided we know the key. But there are cases where we would like our tables to be in read-only format so that the values present inside the table cannot be modified.There are many benefits for this particular approach as we can make use of such read only tables in storing information that we don’t want anyone to mutate, like storing data of employees.In order to make any table a read only table we make use of the setmetatable() function along with __index and __newindex ... Read More
The idea of passing Lua script from C++ to Lua includes the fact that we will have to load the libraries and header files as Lua is ANSI C, and if we are coding in C++, we will need to enclose the #includes in extern “C”.The old and mostly used approach would be to load the libraries that Lua provides and then simply call the C++ function from Lua.In order to load the script from C++ to Lua, we need to set up and shutdown the Lua interpreter and we can do that with the help of the following code.ExampleConsider ... Read More
There are several occurrences when we want to get the integer value of a number and also the fractional value that the number has if any, so that we can use either or both of these values.Lua provides us with a math.modf() function that we can use to find the integer value along with the fractional value if the number has any.Syntaxmath.modf(number)The math.modf() function returns two values when we call the function, the first value is the integer value of the number and the second returned value is the fractional value of the number if it has any.ExampleLet’s consider a ... Read More