increment

问题 I understand how optionals work, but this is throwing me for a loop. I have a variable called num and I want to increment it, so I did the following: var num:Int! = 0 num++ //ERROR - Unary operator ++ cannot be applied to an operand of type Int! But for some reason Swift won't let me increment a force unwrapped Int , even though it is supposed to be treated like a regular Int with the capability for nil behind the scenes. So I tried the following, and it worked: var num:Int! = 0 num = num + 1

问题 What is the idiomatic Common Lisp way to increment/decrement numbers and/or numeric variables? 回答1: Use the built-in "+" or "-" functions, or their shorthand "1+" or "1-", if you just want to use the result, without modifying the original number (the argument). If you do want to modify the original place (containing a number), then use the built-in "incf" or "decf" functions. Using the addition operator: (setf num 41) (+ 1 num) ; returns 42, does not modify num (+ num 1) ; returns 42, does

问题 What is the idiomatic Common Lisp way to increment/decrement numbers and/or numeric variables? 回答1: Use the built-in "+" or "-" functions, or their shorthand "1+" or "1-", if you just want to use the result, without modifying the original number (the argument). If you do want to modify the original place (containing a number), then use the built-in "incf" or "decf" functions. Using the addition operator: (setf num 41) (+ 1 num) ; returns 42, does not modify num (+ num 1) ; returns 42, does

问题 I'm having a UserID field in my table and I need to get that value in my app and whenever I would like to add a new record it should increment by value '1' . So this is how I'm trying to get the last ID enetered from my table. For Example I'm having a value as "A000" and I need to increment that value by '1' so that it should become "A001" and so on..and after 'A999' as pointed out by PinnyM' it should become 'A1000' . I don't want to write any stored procedures or anyother way from database

问题 I have one table called customer_master that includes a column called cust_id with autoincrement set to 1. When we try to insert records its working fine and inserted records like cust_id 1, 2, 3 and 4 are inserted, but when an error is generated in the insert command we do a transaction rollback, this means that cust_id 5 is not inserted, but when we are insert another record, cust_id generates 6. It skips cust_id 5. I want to set it up so that if any error is generated in the insert command

问题 I have a table with a column called "IP", and I would like to create another column in the same table "YTD_IP" which would give the cumulative year-to-date sum of "IP" (innings pitched) for any given game in a year reflecting the sum of innings pitched in games (rows/events) that preceded it in the same season. Once there is a change in year, I'd like the sum to start at 0 again. Here is a sample of data of columns "PIT_ID", "YEAR_ID", "IP", and what I'd like to see the "YTD_IP" column look

问题 I am currently trying to increase the value of an attribute belonging to every agent of the same breed. Every frame the attribute should increase by a pre-determined value, in this case 1. ask breed [if attribute < max-value [set attribute attribute + 1]] I have two agents of this breed in the model and they both change the attribute at the same pace i.e tick0: 100 (100 is the starting value) tick1: 100 tick2: 101 tick3: 103 tick4: 106 tick5: 110 tick6: 121 tick7: 128 There seems to be a

问题 I'm currently stuck in vim trying to find a search/replace oneliner to replace a number with another + increment for each new iteration = when it finds a new match. I'm working in xml svg code to batch process files Inkscape cannot process the text (plain svg multiline text bug). <tspan x="938.91315" y="783.20563" id="tspan13017" style="font-weight:bold">Text1:</tspan><tspan x="938.91315" y="833.20563" id="tspan13019">Text2</tspan><tspan x="938.91315" y="883.20563" id="tspan13021">✗Text3<

问题 In javascript I have a variable that I push to console.log then increment it and push it to the log again, which shows the below in the Chrome Dev Tools. This variable has done some freaky stuff, like if I try to use the += operator to add to it, it actually puts the added value after the number (for example if x=5 and I did x+=3 , x would equal 53 ). The really boggling part of this is that incrementing it with ++ works as expected, but my question isn't why that's happening but rather why

问题 I recently started learning Python, and the concept of for loops is still a little confusing for me. I understand that it generally follows the format for x in y , where y is just some list. The for-each loop for (int n: someArray) becomes for n in someArray , And the for loop for (i = 0; i < 9; i-=2) can be represented by for i in range(0, 9, -2) Suppose instead of a constant increment, I wanted i*=2 , or even i*=i . Is this possible, or would I have to use a while loop instead? 回答1: As you