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问题 When I try to insert the below into my MySQL INSERT INTO `rooms` (`id`, `ip`) VALUES ('131213', '-259857341'); I fails with the follow error: Warning: #1264 Out of range value for column 'ip' at row 1 I am looking around but haven't found how to fix or work it out... My field is unsigned int which should work just fine for that entry. What is the problem and how do I solve ? I am using unsigned int because I wanted to store ips using inet_ntoa/aton. EDIT: I am using unsigned INT as recommend

问题 This question already has answers here : How to convert String to int in C (4 answers) Closed 5 years ago . Given that I have the following: char str[] = "1524"; int nr; I would like to get the number 1524 in 'nr'. What's the best way to achieve that in C? 回答1: The best with error detection is strtol() #include <errno.h> #include <stdlib.h> char str[] = "1524"; char *endptr; errno = 0; long l = strtol(str, &endptr, 10); if (errno || *endptr != '\0' || str == endptr || l < INT_MIN || l > INT

问题 Given a number number such that its digits are grouped into parts of length n (default value of n is 3) where each group represents some ascii value, I want to convert number into a string of those ascii characters. For example: n number Output ================================== 3 70 F 3 65066066065 ABBA 4 65006600660065 ABBA Note that there is no leading 0 in number, so the first ascii value will not necessarily be represented with n digits. My current code looks like this: def number_to

问题 a = 1 print hex(a) The above gives me the output: 0x1 How do I get the output as 0x01 instead? 回答1: You can use format : >>> a = 1 >>> '{0:02x}'.format(a) '01' >>> '0x{0:02x}'.format(a) '0x01' 回答2: >>> format(1, '#04x') '0x01' 回答3: Try: print "0x%02x" % a It's a little hairy, so let me break it down: The first two characters, "0x" are literally printed. Python just spits them out verbatim. The % tells python that a formatting sequence follows. The 0 tells the formatter that it should fill in

问题 I have a very simple rating system in my database where each rating is stored as an enum('1','-1'). To calculate the total I tried using this statement: SELECT SUM(CONVERT(rating, SIGNED)) as value from table WHERE _id = 1 This works fine for the positive 1 but for some reason the -1 are parsed out to 2's. Can anyone help or offer incite? Or should I give up and just change the column to a SIGNED INT(1)? 回答1: Yes, I'd suggest to change the type of the column. The issue becomes clear when you

问题 This question already has answers here : How to nicely format floating numbers to String without unnecessary decimal 0? (25 answers) Closed 5 years ago . How do I remove trailing zeros in a String value and remove decimal point if the string contains only zeros after the decimal point? I'm using the below code: String string1 = Double.valueOf(a).toString() This removes trailing zeros in (10.10 and 10.2270), but I do not get my expected result for 1st and 2nd inputs. Input 10.0 10.00 10.10 10

问题 Does anyone know what the difference is between these two types? The docs only refer to Int but Xcode 6 auto complete only gives me Integer when I type. I started using Integer when porting code only to find that you have to cast between the two types. For instance the following code gives the error Could not find an overload for '+' that accepts the supplied arguments . var number1 : Int = 5 var number2 : Integer = 10 number1 + number2 回答1: An Int is the type whilst an Integer is a protocol

问题 $a = '88'; $b = '88 8888'; echo (int)$a; echo (int)$b; as expected, both produce 88. Anyone know if there's a string to int function that will work for $b's value and produce 888888? I've googled around a bit with no luck. Thanks 回答1: You can remove the spaces before casting to int : (int)str_replace(' ', '', $b); Also, if you want to strip other commonly used digit delimiters (such as , ), you can give the function an array (beware though -- in some countries, like mine for example, the

问题 I need to make a 40 digit counter variable. It should begin as 0000000000000000000000000000000000000001 and increment to 0000000000000000000000000000000000000002 When I use the int class, it cuts off all the zeros. Problem is I need to increment the number and then convert it to a string, with the correct number of leading zeros. The total size should be 40 digits. So if I hit 50 for example, it should look like this: 0000000000000000000000000000000000000050 How can I do that and retain the

问题 I'm using C (not C++). I need to convert a float number into an int . I do not want to round to the the nearest number, I simply want to eliminate what is after the integer part. Something like 4.9 -> 4 .9 -> 4 回答1: my_var = (int)my_var; As simple as that. Basically you don't need it if the variable is int. 回答2: Use in C int C = var_in_float; They will convert implicit Thank you 回答3: If you want to round it to lower, just cast it. float my_float = 42.8f; int my_int; my_int = (int)my_float; //