substring | 易学教程

Substring from NSString [closed]

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问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago . I am using NSString and I want to get a substring of it that contains the first 20 characters of my string. How can I do that? 回答1: You can use substringToIndex . NSString *mystring = @"This is a test message having more than 20 characters"; NSString *newString = [mystring

Lucky Substring（CodeForces - 122B）

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Input 047 Output 4 Input 16 Output -1 Input 472747 Output 7 题意：给出的字符串的子串满足下面3个条件，输出字典序最小的那个。（1）只含有4或7（2）子串中个数多的优先（3）不能有前导0 思路：因为n<50,所以可以先找出所有字串，然后排序，之后输出满足条件的第一个。关键就是如何存储那里，我是先用S数组存出所有字串，顺带写个map标记一下个数，最后就是cmp排序函数了。 #include <iostream> #include<cstring> #include<stdio.h> #include<algorithm> #include <vector> #include<iomanip> #include <queue> #include<stdlib.h> #include<time.h> #include<map> #include<stddef.h> using namespace std; string S[101010]; map<string,int> ma; bool cmp(string p,string q){ if(ma[p]==ma[q]) return p < q; return ma[p]>ma[q]; } int main() { string s; cin>>s; int n=0; for

dfs 感悟

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感悟: 1. 什么时候用排列组合问题? 看看结果有ArrayList? 所求的容器有多个结果值-且各个结果值之间只是顺序,或长度不同,但是来源(存在有显性隐性输入值)都是一样的-- 正是排列组合的根本. 数组, 字符串 2. 关键点: 递归函数里面加入容器, 结果值--操作的元素---不断地操作结果中的值, 输入值, (判断访问过没有—看是否要求重复、位置计数器)。 3. 二叉树的回溯法有单独的模板 5.10 4. //元素没有重复 if (list.contains(nums[i])) { continue; } 5. 元素有重复必须先sort,且要求递增顺序 for (int i = pos; i < nums.length; i++) { //画图得到必须要跟前一个节点的值不同并且不是第一次循环进入的点(不然会空指针异常, 或者同一层次(pos进入)的点,　　　　　　即同一个递归函数不能跟后面的值一样) if (i != pos && nums[i] == nums[i-1]) { continue; } 6. 元素有重复必须先sort,且答案之一的顺序无要求。 for (int i = 0; i < nums.length; i++) { //保证当前元素递归到下一次时不再次访问 if (visited[i] == 1) { continue; } /

How SubString,Limit Using C? [closed]

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问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 2 years ago . Section#1 #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> int main(int argc, char **argv) { static const unsigned char text[] = "000ßh123456789"; int32_t current=1; int32_t text_len = strlen(text)-1; ///////////////////////////////// printf("Result :

R语言 substring() 函数：提取字符串的一部分

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substring()函数的基本语法是： substring(x,first,last) 以下是所使用的参数的说明： x - 是字符向量输入。 first - 是第一个字符要被提取的位置。 last - 是最后一个字符要被提取的位置。 eg. result <- substring(“Extract”, 5, 7) print(result) 当我们上面的代码执行时，它产生以下结果： [1] “act” 来源： CSDN 作者：铃儿响叮当1987 链接： https://blog.csdn.net/weixin_44612629/article/details/103906953

Count subsequences in hundreds of GB of data

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问题 I'm trying to process a very large file and tally the frequency of all sequences of a certain length in the file. To illustrate what I'm doing, consider a small input file containing the sequence abcdefabcgbacbdebdbbcaebfebfebfeb Below, the code reads the whole file in, and takes the first substring of length n (below I set this to 5, although I want to be able to change this) and counts its frequency: abcde => 1 Next line, it moves one character to the right and does the same: bcdef => 1 It

substring详细用法，截取不行就用替换

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SUBSTRING 返回字符、binary、text 或 image 表达式的一部分。有关可与该函数一起使用的有效 Microsoft® SQL Server™ 数据类型的更多信息，请参见数据类型。语法 SUBSTRING ( expression , start , length ) 参数 expression 是字符串、二进制字符串、text、image、列或包含列的表达式。不要使用包含聚合函数的表达式。 start 是一个整数，指定子串的开始位置。 length 是一个整数，指定子串的长度（要返回的字符数或字节数）。 substring() ——任意位置取子串 left() right() ——左右两端取子串 ltrim() rtrim() ——截断空格，没有trim()。 charindex() patindex() ——查子串在母串中的位置，没有返回0。区别：patindex支持通配符，charindex不支持。函数功效：字符串截取函数，只限单字节字符使用（对于中文的截取时遇上奇数长度是会出现乱码，需另行处理），本函数可截取字符串指定范围内的字符。应用范围：标题、内容截取函数格式： string substr ( string string, int start [, int length]) 参数1：处理字符串参数2：截取的起始位置（第一个字符是从0开始）

Modify non immutable object, java

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问题 I am confused with this example : StringBuilder a = new StringBuilder("abcde"); String subStr = a.substring( a.indexOf("a") , a.indexOf("c") ); int leng = a.length(); char ch = a.charAt(4); System.out.println( subStr + " " + leng + " " + ch); //the result will be : subStr = abc , leng = 5 ch = e My question is : Why ch = e and it doesn't create an Exception ? My thinking: I have one StringBuilder, a non immutable object and if I use a method on the object it will return me a new value of the

How can we make maximum number of palindromic substrings by rearranging the characters in a string?

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问题 A string is called a substring of another string, if it can be obtained from that string by dropping some (possibly zero) number of characters from the beginning and from the end of it. For example, abc , ab , and c are substrings of the string abc , while ac and d are not. Let's define a palindromic count of the string as the number of its substrings that are palindromes. For example, the palindromic count of the string aaa is 6, because all of its substrings are palindromes. And the

Is there a way to find a last substring?

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问题 my brain might be really tired but i coudn't seem to work my head around this simple query.. I want to extract a last substring within delimiters such as ',' from a column? i was thinking about using REVERSE or RIGHT.. but the results are coming off as really bizarre... Lets say i have a table column 'DESCRIPTION' in a table LOANS with an entry Changed Loan Laptop from "IT-X130E-10" to "IT-X130E-9". and i want the last substring IT-X130E-9 within delimiters '"' hope its clearer now 回答1: Can