position | 易学教程

C function strchr - How to calculate the position of the character?

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问题 I have this example code for the strchr function in C. /* strchr example */ #include <stdio.h> #include <string.h> int main () { char str[] = "This is a sample string"; char * pch; printf ("Looking for the 's' character in \"%s\"...\n",str); pch=strchr(str,'s'); while (pch!=NULL) { printf ("found at %d\n",pch-str+1); pch=strchr(pch+1,'s'); } return 0; } The problem is, I don't understand, how this program calculates the position of the looking character. I think it has something to do with

php array get positions of the specific value

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问题 I have one array and I want to get the positions of one specific value Example: $my_array = array(0,2,5,3,7,4,5,2,1,6,9); My search is Number 5 the positions of Number 5 in array was ( 2 and 6 ) If i call the array_search function, always returns the first position in array witch is 2 . Is there anyway to get the two ore more positions of specific value? 回答1: Use array_keys with the optional search parameter, that should return all of the keys. $matches = array_keys($my_array, 5); 回答2: Have a

Position Userform differently for each ActiveCell Clicked

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问题 I have a UserForm of a MonthView and DTPicker that will populate when certain cells are clicked. I have the form positioned for directly below the first cell, but would like it to populate right under each active cell that I tell it to activate on. My current activate code to position the user form is: Private Sub UserForm_Activate() With frmCalendar .Top = Application.Top + 340 .Left = Application.Left + 330 End With End Sub and my worksheet selection change code, which will launch the

Powershell Replace Characters in a String

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问题 Using powershell, but open to other potential solutions.... I have a long string. I need to replace several sequences of characters by position in that string with a mask character (period or space). I don't know what those characters are going to be, but I know they need to be something else. I have written code using mid and iterating through the string using mid and position numbers, but that is a bit cumbersome and wondering if there is a faster/more elegant method. Example: Given the 2

Set div height between two divs

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问题 I am trying to get a div height take the remaining space between two divs. <div id='company_col' class='contact_columns'> <div id='company_title' class ='col_title'> <h3>Company</h3> </div> <hr> <div id='company_list' class='contact_lists'> </div> <div id='company_edit_bar' class='edit_bar'> <div id='company_add_btn' class='edit_btn'> <i class='fa fa-plus' aria-hidden='true'></i> </div> <div id='company_delete_btn' class='edit_btn'> <i class='fa fa-minus' aria-hidden='true'></i> </div> </div>

位置角度平移旋转，“乱七八糟”的坐标变换

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本文转载自微信公众号ROBOTICS 原作者：CC 编辑：古月居原文链接： https://mp.weixin.qq.com/s/eOq5QweS-VIg2e0qmkihMw 今天我们要讲所有学习机器人学的人都需要具备的一项基本技能——坐标变换。看明白这篇文章，你需要一点基础的向量和矩阵知识，不用多，只要知道向量的加减，点乘（内积）；矩阵的定义、加减乘逆以及转置；还有矩阵与向量的乘法就够了。机器人学为什么需要坐标变换呢？因为控制一个机械臂的根本，就是弄明白每一个关节的joint position与end effector的position and orientation的关系，用更简洁的话来讲，就是joint space与operational space之间的互相映射关系。这里有两个小说明：不仅仅是位置/角度的映射关系，也包括速度、加速度、力或扭矩的映射关系所有我直接用英文而没有翻译的词汇，都是我在第一篇文章中解释过的重要概念好了，接下来就让我们暂时不谈机器人，先把让很多人觉得头疼的坐标变换搞明白。坐标系(coordinate system) 描述空间位置、速度和加速度，大部分都是用笛卡尔坐标系，也就是大家熟知的三个互相垂直的坐标轴组成的坐标系。我只想强调几个地方：像题图那样的彩色坐标系，若无特别说明，都是 rgb(红绿蓝）依次对应 xyz

Position absolute prevents browser to calculate correct height. Is it possible to fix this issue

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问题 I am developing a browser game. Until now i was using all position absolute. Because of that i have to set every page height myself. Now trying to pass this problem but since i used position absolute at my everything it always prevent browser to calculate correct height of div. Is it possible to achieve this. I mean for example i have div and inside many divs which uses position absolute feature. So i want this main div to calculate its height automatically which would be sum of nested divs

jQuery FancyBox : fixed position of popup with respect to window while scrolling

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问题 How can I fix the position of fancybox popup window on the screen when scrolling the page? Is there any options in this plugin or I have to define it using css ? 回答1: From the API page, centerOnScroll seems to be what you want: Key: centerOnScroll Default Value: false Description: When true, FancyBox is centered while scrolling page 回答2: The problem with simply using the centerOnScroll API option is that while you scroll up and down the page, you will notice that your fancybox window has to

Who wins out of css top/bottom?

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问题 If you have a div that sits at the 'bottom' like so: <div id="box" style="position: absolute;width: 10px;height: 10px;bottom: 0px;"></div> and then if you were to change the position using 'top'... $('#box').css({'top':'0px'}); what happens to the 'bottom' css command and what decides who (top or bottom) wins? Should I cancel bottom somehow at the same time as setting top? Ideas: $('#box').css({'top':'0px','bottom','none'}); $('#box').css({'top':'0px','bottom',''}); It never occurred to me

Plot vertices at the same position

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问题 Is there a method to plot the shared nodes of 2 graphs at the same position? E.g., two graphs g1 = graph.ring(5) V(g1)$name=c('node1','node2','node3','node4','node5') g1 = g1 - V(g1)[1] g2 = graph.ring(5) V(g2)$name=c('node1','node2','node3','node4','node5') g2 = g2 - V(g2)[2] There are 3 nodes are exactly the same for g1 and g2. How can I plot them with the same nodes having same position so that its easy to compare the difference? par(mfrow=c(1,2)) plot(g1, vertex.label=V(g1)$name) plot(g2,